Nick Townsend: All the rage as a player but can Keane cut it as boss?

The Irish midfielder has always relished an existence close to the edge. Provocative in his views and actions, he has always been a potentially combustible mixture: both leader and antagoniser. If his statement eluded the United radar, they have refused to respond with a counter-strike. Thus far, we understand that the captain of United, who formerly also held that responsibility for his country before availing Mick McCarthy of certain of his beliefs - namely, "I didn't rate you as a player; I don't rate you as a manager; I don't rate you as a person" - has been accorded no immediate response from his club.

Nevertheless, United will no doubt take the opportunity before the next transfer window of identifying possible replacements for Keane, who, whether he departs within the next 12 months or remains at Old Trafford to make the transition to coach, is approaching the midwinter of a career following a glorious summer. Bayern Munich's charismatic playmaker Michael Ballack, a leader like Keane and captain of club and country, is an obvious choice for Sir Alex Ferguson, particularly as his contract expires after next year's World Cup. Keane is said to have been frustrated that the club had not moved in ahead of Chelsea for the powerful Michael Essien.

If not Ballack, what of the Dane Thomas Gravesen, late of Everton, but currently of Real Madrid, a doughty tackler and inspired passer? He and Ballack are 29. Two years younger is Fulham's daddy-longlegs, Papa Diop, blessed with a dynamic shot from distance and a huge desire to get forward. None are exactly in the Irishman's mould, but as Carlos Queiroz, Ferguson's assistant, has observed, Keane is irreplaceable. "You can't replace the great players: Pele, Maradona, Eusebio - or Roy Keane. You have to create new players and new teams." Just as Arsène Wenger must restructure an Arsenal denuded of Patrick Vieira's potent influence, the loss transcends mere playing ability.

Why should Keane depart? He is comfortably domiciled in Hale, where his children are educated. He is extraordinarily well-paid. Indeed, he brought a similar issue to a head six years ago with TV comments that he might play for another club; an £80,000-a-week agreement with United was completed.

It could be contended that this time he really does want to abandon the nest-egg, especially as he suspects Ferguson is grooming Queiroz as his successor. There is an argument that to be so inextricably linked with one club and one manager - never mind the three seasons with Nottingham Forest in the early Nineties under Brian Clough - can limit your job-seeker potential; even a candidate with as impressive a CV as Keane.

He has certainly dismissed playing for another English club. It is not inconceivable but difficult to imagine him managing one. Celtic would enthuse him, if the opportunity arose, but would they yield the challenge he would undoubtedly crave? Perhaps in the short term. That club have now stabilised under Gordon Strachan, but they could still beckon, offering Keane a player-manager role.

Or maybe his journey will take him back to Ireland if, as anticipated, that nation fails to qualify for the World Cup. What an irony that would be... "Nobody would play for me, but we'd have great facilities," Keane had jested back in 2002 when it was suggested to him, during that McCarthy contretemps over poor preparations, that he could be a Republic player-manager of the future.

Former team-mates such as Mark Hughes have immediately been proclaiming Keane's managerial potential, although he wouldn't be the last on-field general to fail once transported to that curious, often lonely, land of tracksuit, cones and tactic sheets. Bobby Moore, no less, was one.

Respect from players would be a crucial advantage, though both Wenger and Jose Mourinho, neither of them top- quality players, have proven that it is no longer necessary to display "yer medals" in order to galvanise a group of players. His inherent passion would be another virtue. But exhorting and at times raging at his team-mates as captain is one thing; possessing the temperament of guv'nor to motivate those who maybe do not possess his instinctive desire to be a winner, that is quite another.

Still, when the day comes it will be fascinating to discover if Keano can cut it.