Sideline Cut: As with athletes, the toughest decisions for sports managers and icons come with realising the right time to leave. It must be a fiery demon indeed that burns inside Alex Ferguson to encourage him to commit three more years of his life to Old Trafford.

Will the old place still be named that when the Scot finally packs his baubles and photographs into cardboard boxes and vacates the Gaffer's room? And even if it is, will he still recognise it as the same ground at which he transformed a club that was the listing flagship of English football into a veritable empire and finally a whored-out brand name? All this week the Scotsman has spent bickering with his Gallic nemesis, Arsene Wenger, about whether Thierry Henry will appear at today's FA Cup final.

The stand-off is as tedious and harmless as two grumpy old men rowing about whose turn it is to cut the neighbouring hedge. Chelsea have long won the league title, Liverpool have become an unlikely example of old-fashioned heroism and Manchester United's last hope of seasonal silverware lies with a competition Ferguson could afford to disdain just a few short years ago.

It is as though Wenger and Ferguson were taking comfort in the sounds of their own grouchy, opposing viewpoints. The danger is that to public ears it is like the last roar of the dinosaur.

You search in vain for the obvious attractions for Ferguson of staying on as boss. However one regards Manchester United, there was something saddening about the way a blueblood establishment could be scooped up by someone like Malcolm Glazer, a Floridian munchkin who looks like he has just stepped off a St Patrick's Day parade float.

It is true that by swimming with the corporate fishes, Manchester United declared itself a business, open to the same advantages and ruthless mechanisms as the companies with whom it chose to list itself. But you have to believe it also represented something more, at least to some of the fans that live in the city or travel to Manchester each weekend to follow the team. The thrill of following United through the 1990s always escaped me. Alone, the club seemed tailor-made to fit the Premiership model and so thrived while other clubs, most notably Liverpool and Arsenal, until someone had the vision to appoint Wenger, struggled for breath in its slipstream. It was hard to see where the fun was in following a procession of Saturday league wins against Birmingham, Norwich and the like.

But it is undeniable the club and its folklore meant and continue to mean a lot to people who invest time and money in following it. Until this week, Manchester United followers could at least keep alive the pretence that the voice of the people was still audible at Old Trafford. Rightly or wrongly, the arrival of Glazer seems coloured with the sinister. For fans it is as though the club they love has been taken over by aliens. The American may pose in a candy-striped soccer scarf before the new season but his obsessive and bloodthirsty acquisition of a club with which he has no natural empathy does not bode well. Were Matt Busby alive, one imagines him bewildered and profoundly sad.

Without the dominance over which Ferguson presided through the 1990s and the boardroom ambitions led by Martin Edwards, Manchester United could conceivably still be plodding along in the grossly underachieving manner that characterised them through the 1970s and 1980s. Instead, a combination of driven individuals sought to reclaim what they perceived to be the club's rightful place in the global hierarchy and the conclusion has been its plain-weird stabling with the Tampa Bay Buccaneers.

Perhaps some sense of loyalty and the dauntless competitor within Ferguson have compelled him to try and steer the club through the early and potentially volatile years of its Americanisation. The Scot has been typically canny about the implications of the Glazer takeover and the widespread predictions that the family will stick a Ronald McDonald cap on the Matt Busby copper statue if the bucks are right.

Deep down, Ferguson must feel in some way responsible for the fact that all of a sudden an American oddball holds the reins.

Former United director Greg Dyke this week stated the Glazer takeover originated in the feud between Ferguson and the Irish powerbrokers JP McManus and John Magnier. His theory is that the racing magnates bought their 29 per cent shareholding to demonstrate their power to their former friend, thus leaving the club vulnerable to precisely the kind of takeover that has occurred. If there is any truth in that, it must also weigh heavily on the Scot.

Glazer's representatives undoubtedly offered handsome terms to Ferguson, anxious to keep the cult figure on board while they implement the fiscal policies designed to recoup the staggering £540 million debt with which they have saddled their new acquisition.

There is the sense now that United are drifting through nothingness and that although the team will play today and next season it is all a bit illusory. The situation should offer guidance for clubs like Liverpool or Arsenal, whose directors feel honour bound to chase the backing of big-money moguls. Maybe it is better to stay local, to stay modest and achieve the kind of real, identifiable glory that Liverpool touched upon this season, even if it only comes around once or twice in a lifetime.

It is hard to see even someone of Ferguson's work ethic and passion and stubbornness return United to spectacular heights over the next couple of seasons.

Wedded to a grassroots managerial philosophy and no more immune to age than other men, Ferguson arguably faces a tough final lap of his sporting life. It is highly unlikely the new broom at Manchester United will approve the kind of spending necessary to restore onfield fortunes.

As to the burning question of who is going to replace Roy Keane, the answer is nobody. Keane is irreplaceable. The money is too easy now and the lifestyle too soft to breed a player with his instinctive, brilliant ferocity - and Ferguson, his arch-champion, must know that. True, watching Ronaldo and Rooney mature may prove enjoyable for the manager but the Portuguese winger is surely the oil in the machine rather than a driving cogwheel. And already last summer's talk about Rooney seems wildly previous.

Win or lose today's old FA show trophy, the pressure will be on Ferguson to deliver the goods next season just as it was in his first joyless seasons at Old Trafford, when it was an ordinary club trading on a luminous past.

Had he got out after the extraordinary Champions League final blitz of 1999, his reign would have been perfect. Instead, he faces a muddy and uncertain final few years in the game, and if he fails he will be answerable to the great American sales tradition and, no less than Willie Loman, Sir Alex will be out in the cold.