If only it were that simple. When Keegan made the latter choice on that 8 January 1997, he unwittingly triggered a sequence of circumstances that affect the club to this day. What he can never have imagined is that some two and a half years on the turmoil afflicting Newcastle would impinge on his role as England coach.
The "soap opera" at Newcastle, as he referred to it, is not directly of his making. It is down to the Board and Ruud Gullit; and, some would suggest, Alan Shearer. But when Keegan's captain and the first name he scribbles on the team sheet is embroiled as a central character in the intrigue at St James' Park, when that man is regarded as a natural successor to Gullit, then its effect on the morale of the entire England squad cannot be understated.
"Football is full of surprises," Keegan said when naming the 37-year- old Stuart Pearce, two years' retired from international football - and, coincidentally, a Gullit write-off. But there was never going to be a similar intake of breath when it came to Shearer's name, despite his demotion to the bench against Sunderland, Gullit's last match in charge. Keegan's belief in the player he lavished pounds 15m on is unconditional, and may be rewarded through England's resurrection from third place in Group Five to Euro 2000 qualification; it may also be misplaced.
Keegan implored us to scrutinise Shearer's statistics when considering his continued potency as a goalscorer. But while the England coach is almost evangelistic in his belief, the evidence hardly supports his case. Last season in 30 club appearances, he scored eight goals from open play; in nine England games, he netted twice.
From being England's superman, which he certainly approached at Blackburn, he has perhaps got a touch too close to the kryptonite. His powers are demonstrably on the wane and a tendency to a more robust approach is simply because his pace has been restricted by major surgery.
Notwithstanding that, Keegan would retain him anyway because of what he describes as his "passion and hunger". Keegan regards his sheer presence as inspirational. Unpalatable though it may appear, in many quarters that quality, too, is being questioned; not least presumably among those players who would usurp his crown. Certainly, his frequently curmudgeonly manner does nothing to enhance his questionable ambassadorial credentials, and even Keegan concedes: "When he sits down with you, he's the most honest person you could meet. When in front of the press, like a lot of people, he will come out with his pads on and his bat to fend off questions."
The implication is that his public demeanour is something Shearer will have to brush up on should he ever enter management, which may be just around the corner rather than on the far horizon the way developments are unfolding at St James' Park. For Keegan, there is merely sadness. "I thought Kenny [Dalglish] was a great appointment. It didn't work. I thought that Ruud Gullit was a great appointment. Who's to know about the future?" he said. "The greatest thing about the club is and always will be the supporters, not the Sir John Halls and the Ruud Gullits, even the Alan Shearers. They will all go, but the black and white shirts will keep on coming."
However, the England coach sees the humorous side when it is suggested that being involved in some managerial role, sooner rather than later, could jeopardise Shearer's England career. "It might worry me as England manager if he does well," said Keegan, who added in a more subdued tone. "From what I've read, it seems that it has been said to Alan, 'One day, you'll probably manage this club.' I think that Alan's said that one day he would like to, but it's a long way away. At the moment, he's still got an awful lot of football in him."
Keegan added: "Alan Shearer is a special person, so don't underestimate him. I see him as being a manager. But you can be manager the rest of your life. My advice to him would be, just stick that on the back-burner. There's nothing beats playing."
Of course, a bagful of goals against Luxembourg next Saturday at Wembley may ease many of those doubts regarding the captain, though that result - bar an unlikely draw or unthinkable defeat - will be largely irrelevant. Poland in Warsaw the following Wednesday is the crucial contest, and there will be no excuses then for Keegan. No Sol Campbell or Graeme Le Saux, but otherwise, allowing for some lack in match fitness in the likes of Michael Owen and Tony Adams, he has had the pick of England's elite.
His decision to name Chris Sutton and Robbie Fowler ahead of Andy Cole, Dion Dublin and Emile Heskey - the latter pair in particularly fine fettle - will either be vindicated, or as Keegan accepts: "I know I'm going to get the flak."
Cole's omission is not altogether surprising, based on a largely insipid performance against Sweden. But to be spurned by not one, but now two England coaches, will test his forbearance to the limit. Keegan admits he is not sure what response he will receive. "You can spend three years with him like I did at Newcastle and, I've got to be honest with you, you never really get to know Andy Cole," he said. "He's had a rejection before at Arsenal. If he sees this as rejection, which he's bound to do, he's got the character to bounce back.
"In his first game for me, against Poland, I thought he did terrific, but you have to go on from that. You might say, 'Did Alan Shearer play any better?' But the answer is, Alan Shearer has proved it at this level. It sounds a bit cruel, but it's like when young kids come into a League side, they've got to do even better than seasoned pros to keep their place. I want to look at other options which are more interesting for me."
Owen appears the most likely to partner Shearer against Luxembourg, possibly with a third forward, like Teddy Sheringham, dropping off behind them. But if he does not present himself match-fit, the combination of the captain and Sutton, in a re-run of the old Blackburn SAS, could be an intriguing one.
Keegan has always maintained that he would be "less interested in players who could take it or leave playing for England", which would appear to count against Sutton. But he declared: "It's a fresh page. I've picked Chris because he gives me an option. How many players like Chris Sutton are there in this country? He's pretty unique, the way he plays."
A partnership with Shearer, he agreed, "could be a definite advantage". As Gullit may have found, also, had he possessed the humility to do so and understood the power of the Geordie idol on Tyneside. By the time Newcastle visit Stamford Bridge, if not this week, he may have learnt a harsh lesson.