A Today programme without Humphrys would leave James Naughtie as the undisputed heavyweight of morning radio.
When Naughtie first joined the programme after the death of Brian Redhead there was undisguised rivalry between the two lead presenters over who would do the big interviews and be regarded as the main presenter of the show. The BBC has been conspicuous in never stating which is the senior figure, and it claims to have always seen them as equals.
Nevertheless the 56-year-old Welshman's taste for the bruising, ten-past- eight political interview and his 13 years on the programme have made him seem to the public like the programme's chief presenter. Naughtie, however, is no slouch when it comes to an on-air fight himself. With Humphrys gone, he would be the only real candidate to take on the legacy of Brian Redhead.
This, of course, again leaves Sue McGregor playing second string. She has complained on the record in the past that there is a machismo pervading news broadcasting which has kept her back. Now BBC insiders believe that a core team based around Naughtie and McGregor is likely to appeal to listeners, and she would become more prominent.
If Humphrys leaves Today, the show would be down to two main presenters after Anna Ford left in May to become the anchor of the BBC1 One O'Clock News.
However there are plenty of people waiting in the wings, thanks to experiments with presenters during the summer. Ed Stourton, who replaced Nick Ross as presenter of Radio 4's Phone-In Show, is as experienced as anyone the BBC has to call on, and would seem the most obvious candidate to become a full-time member of the team.
Insiders at the BBC say he is the guest presenter who most suits the programme's tone. However, it is rumoured that the show's bosses may want to use the opportunity of change to make the programme more accessible. That could count against Stourton, who some on the programme believe to be too highbrow, and others that his presentation is too dry.
Popular, but less experienced, is the Woman's Hour presenter Winifred Robinson. She was given much publicity when she began slots on the programme, but strangely has not been as regular a presenter as had been expected. Today reporters likely to take a presenter's role are Allan Little, already something of a regular, and Tom Fielden.
If the BBC really wants to overhaul the programme - and it suffered a wobble in quality when its length was extended by the schedule change last year - the corporation may decide to bring in an outsider deemed to have the quality of accessibility. According to BBC sources, such names could include Nicky Robinson from Radio 5's live breakfast news show and Independent columnist and Newsnight presenter David Aaronovich. Also in the frame and making guest appearances on the programme already would be arts features correspondent Mark Cole and the reporter Alex Brody.