If you take everything Mr Blair says at face value, the answer is that they will still be in the flat above the shop. He promised us a "full Parliament", which could imply he is staying until 2009, and is certainly taken by those loyal to him to mean no earlier than 2008.
Members of his immediate circle of advisers, ministers and former ministers are positively encouraging him to stay through the coming year. They don't think anyone else will see the Blairite reform agenda through. They may also have worries about their job prospects under a new prime minister.
And there is the matter of the Blair "legacy". Sooner or later, major public figures are afflicted by an anxiety about what posterity will say about them. Tony Blair is anxious not to be remembered just as the prime minister who took us to war in Iraq, as Anthony Eden is remembered for Suez. He stays on, determined that better state schools, a more patient-friendly NHS, and a fall in yobbish behaviour and petty crime will be his legacy. But look hard into the tea leaves and you might find them forecasting that Mr Blair will be out of office by October.
What may happened is that in July, as MPs prepare for their long summer break, Mr Blair will hand in his three months' notice, giving the Labour Party time to elect a new leader before politics resumes in earnest in the autumn. And despite the talk from various cabinet ministers of a painless hand-over of power from Blair to Gordon Brown, it is probable that there will be a contested election after he goes.
There are Blairites who would like to see an ultra-loyalist such as the Defence secretary John Reid, or the former party chairman Alan Milburn, give Gordon a run for his money. And even if the Blairites stay out of it, it is probable that someone from the left of the party will have a go, pitching for votes of trade union members by promising better union rights, a higher minimum wage, and state pensions that automatically rise annually in line with the increase in average earnings.
Under this scenario - if it comes to pass - Labour's autumn conference will open in late September with the high drama of an election result being announced to cheering delegates, and the dour face of Gordon Brown breaking into a rare look of joy as his eight-year wait finally ends. The next day's newspapers will then feature front-page pictures of Gordon and his newly elected deputy - Alan Johnson, in all probability - with arms raised in victory salute.
Almost as an aside, one should also mention that the Liberal Democrats appear to be teetering on the verge of making a decision, too. Charles Kennedy is surviving mainly through the lack of an obvious successor. Whether he will still be in office by spring is an open question. David Cameron could end 2006 as the longest-serving of the three main party leaders.
What we will then see is a mazurka-like battle between the new leaders as each tries to build an appropriate image for himself, while simultaneously trying to demolish the images the other two leaders want to project. In politics, successful leaders are those, including Tony Blair or Margaret Thatcher, who project such a vivid sense of what they are that they define themselves. The failures are those defined by events that run out of control, or by what their opponents say about them. There was a classic illustration of this when Tony Blair, as opposition leader, told John Major: "I lead my party; you follow yours." In one devastating sentence, he won the battle of "who defines whom". David Cameron is adroitly engaged in a similar game. He is far too smart to try to attack Tony Blair as an extremist who is only pretending to be a consensus politician. Instead, he is trying to define Tony Blair as a leader who once did good things, but whose time is over, and whose grip on his own party has faltered. "You were the future once," he told him, during their first Commons exchange.
Mr Cameron's repeated offers to help the Prime Minister steer his controversial plans for education through the Commons may sound generous and bipartisan. That is how he wants to sound. Actually, it is an adroit political manoeuvre, part of a strategy known to spinmeisters as "de-coupling".
What Cameron wants to do is open as wide a gap as he can between Tony Blair and the Labour Party, so that when the Prime Minister goes, the Conservatives can tell Labour voters everything they liked about the Labour Party went with him, while everything they distrusted about the pre-Blair Labour party lingers on. If you liked Tony Blair, the subtle message will be, you'll just love David Cameron.
Mr Cameron is also, of course, trying to define Gordon Brown, not as the co-founder of New Labour, but as the biggest roadblock in the way of the reforms that he, Tony Blair, and most reasonable, right-minded people would like to see enacted.
If he has not yet caused an irreparable rift between the Downing Street neighbours, Mr Cameron has certainly rubbed raw nerves of their long, and wounded relationship. Mr Brown and Mr Blair are now profoundly divided over the strategic question of how they should deal with the new, young Tory leader,
Mr Brown and his supporters insist that they must define David Cameron before he has succeeded in defining himself. They argue that Cameron is not a political virgin, but an experienced professional with a long history. He was political adviser to Norman Lamont and Michael Howard; he wrote the Conservatives' 2005 election manifesto; he has shown himself to be more anti-EU even than Michael Howard, and he has toyed with the idea of replacing income tax with a flat tax.
Never mind Cameron's youth, good looks and carefully crafted media image, they argue, attack him for his political beliefs. The public has not made up its mind about Mr Cameron yet. The Brownies want to expose him up as a traditional right-wing Conservative, the friend of wealth and privilege, now, before he has convinced people he is something different.
Frustratingly for Gordon Brown, Tony Blair completely disagrees. The Blairite view is that the Tories made a bad mistake back in 1994, when they rushed in to attack Tony Blair as soon as he had taken over the leadership of the Labour Party, without waiting to get his measure. They did not know whether to attack him as "Bambi" - a basically harmless creature who looked good but was not equipped for the job - or as "Demon Eyes", a threatening figure whose nice smile concealed wild political ideas. They tried both lines, and neither worked.
Blair insists Labour must not repeat this mistake with Cameron. For now, they should play along with Cameron's superficially attractive idea of ending "Punch and Judy" politics and look for issues on which the two parties can agree. If they attack him too early on as right-winger, Mr Cameron might surprise them, face down the backwoodsmen in the Tory party and inaugurate a new version of consensus, One Nation Toryism.
So it makes sense to wait, they claim. Eventually, he will have to produce a policy programme to put before voters and when he does, then is the time to take him on. As one leading Blairite put it, Cameron "needs to be given the rope to hang himself."
This sort of talk sets teeth grinding in frustration over in the Brown camp. It is the sort of talk, they fear, that you hear from a Prime Minister who knows he is not going to have to fight another general election, and quite enjoys the false flattery wafting across from the Conservative leader. Waiting for Cameron to supply the necessary rope could take a very long time. He has delegated the big political issues to various newly created policy groups, who have been given 18 months to report back. By then, Mr Cameron may be such a familiar figure on the political landscape it will be too late to convince voters that actually he is nothing but a neo-Thatcherite with a bike and open-neck shirt.
But if Labour has problems, they are nothing compared with the dilemma facing the Liberal Democrats. The crisis over Charles Kennedy's leadership is not just about the man; it is a crisis of definition for the whole party. Kennedy used a few cleverly chosen themes - pro-Europeanism, an emphasis on civil rights, opposition to the Iraq war and opposition to tuition fees - to make the Liberal Democrats an acceptable berth for voters who did not care for either of the main parties.
But if Cameron succeeds in presenting a human face of the Conservative Party, and Gordon Brown persuades his constituency that New Labour has survived the departure of Tony Blair, but is somehow more detached from the Iraq imbroglio, that does not leave much space in which the Liberal Democrats can operate.
The most intelligent of the party's leaders want it to issue a clear statement of belief in a free-market economy and low taxes, making it a greener, more liberal, more Europe-friendly version of the Conservatives. But the party's rank and file do not want that. They want to raise taxes to pay for more investment in public services, and to create a version of the old Labour Party, minus its links with the trade unions. Whoever is leading them by this time next year will have to guide them through this painful, almost insoluble debate.
The first big problem in the Government's path is the proposed Education Bill, which is to be drafted next month, based on a White Paper published in November. The White Paper has attracted so much flak from the Labour side that if the Prime Minister does meet some of the rebels half way, he will have to rely on the Tories to save him from defeat.
The last time he was put in a position like this, over the Terrorism Bill, Blair preferred what he regarded as an honourable defeat to compromise, which might have looked like opportunistic weakness. But the difference then was that the Tories were opposing him. This time, he is being offered the poisoned chalice of Tory support.
The signs are that not even Blair - for all the delight he seems to take sometimes in facing down rebels from his own party - is so detached from party politics that he will let the Tories help him push through a major piece of domestic legislation against opposition from such mainstream figures as the former education secretary Estelle Morris. Instead, he will aim to do a deal that is enough to give him a majority in the Commons, with or without the Tories.
But where does that leave a Prime Minister who takes pride in being somewhat above party politics, a leader, not a prisoner of his truculent party, like poor old John Major? The number of Labour MPs who are disaffected or simply impatient for a change of leader is sure to keep growing during 2006. They now know that when they are organised, they can put a check on Tony Blair's ambitions. In extreme cases they can defeat him, as they did over the Terrorism Bill. In other circumstances, they can force him to negotiate.
In May, thousands of councillors around the country will have to put themselves up for re-election, defending seats that were last contested in 2002, when Blair was riding a wave of public trust and approval that followed the 11 September atrocities, and the Conservative were led by the luckless Iain Duncan Smith. No one is in serious doubt that hundreds of Labour councillors are going to lose their seats.
The worst results for the Government are likely to be in London, where a clutch of borough councils will pass over into Conservative control. The Tories could end up with more council seats than they have held for 14 years, or longer. On the morning after the results, we can expect Cameron to emerge looking like a winner, while enraged London Labour MPs go on the airwaves to call on Blair to go quickly before any more damage is done.
With his hold on Parliament weakened, his astonishing capacity to win elections called into question, and a youthful Tory leader taunting him as a figure from the past, Tony Blair may decide that the moment has come to quit with dignity. He may even have made that decision already. If he has, there will be three or four people in the country who know, not including Brown, while the rest of us are just guessing.
There again, Mr Blair may have looked at his calendar and noticed that if he stays on until May 2007, he will have done a full 10 years in the job. Or if he can make it through to the end of November 2008, he will have been in power longer than Margaret Thatcher. The thought of a place in the record books may be too good to resist, even if it gives Brown ulcers, and gives Cameron a long, long opportunity to define Gordon before Gordon can define him.
9 Commons returns from recess
10-12 Labour Party spring conference in Blackpool
16 Parliament rises for spring half-term
25 Plaid Cymru spring conference in Carmarthen
27 Commons returns from recess
3-5 Liberal Democrat spring conference in Harrogate
16-19 Green Party spring conference in Scarborough
30 Commons rises for Easter recess
7-9 Conservative Party spring conference in Manchester
18 Commons returns from recess
4 The most important date in politicians' diaries this year. Local elections for councillors will be held in all 32 London boroughs, 36 English metropolitan boroughs, 20 English unitary authorities and 88 English second-tier districts. There will also be simultaneous elections for directly elected mayors in Bedford, Doncaster, Hackney, Hartlepool, Lewisham, Mansfield, Middlesbrough, Newham, North Tyneside, Stoke-on-Trent, Torbay and Watford (though not in London, where it is next held in June 2008). There is one Conservative mayor (Torbay) and one Liberal Democrat (Watford). Of the remainder, four are independent and six Labour. Crewe and Nantwich Borough in Cheshire will also hold a referendum on whether to set up an elected mayor and cabinet system for their council. If adopted, this would make it the 13th UK local authority to have an elected mayor.
25 Commons rises for Whitsun recess
5 Commons returns from recess
25 Commons rises for summer recess
16-21 Liberal Democrat conference in Brighton
21-24 Plaid Cymru conference in Swansea
24-28 Labour Party conference in Manchester
1-5 Conservative Party conference in Bournemouth
9 Commons returns from summer recess
11-16 Scottish National Party conference (venue unknown)