Fergie's departure will take place after Manchester United's game against West Bromwich Albion on 19 May; a game that will mark an incredible 1500 games in charge of the club.
Manchester United were very much a sleeping giant when he took over in 1986, having not won a league title for 26 years. After a slow start, he not only awoke that giant but sent it on a silverware-crazed rampage, dominating English football and breaking arch-rival Liverpool's league title record along the way.
That success has allowed Manchester United to become one of the richest teams in world football (in fact they were the most valuable outright until Real Madrid overtook them this year). A mind-boggling £357m shirt sponsorship deal with Chevrolet is just the latest in a series of lucrative partnerships that have set new financial benchmarks in sports sponsorship.
Their reported revenues in the three months to March 31 this year totalled a tidy £91.7m, despite wages rising by 25% (who knew midfielder Nick Powell was getting paid so much?).
Income like that can only be driven by success on the field, and that is where Ferguson has excelled. Throughout his tenure, Man Utd have developed a reputation for commitment, determination and desire thanks to his unparalleled talent for motivating players, whether that be by standing by them in times of trouble - Rio Ferdinand's missed drug test, Eric Cantona's Bruce Lee impression, Roy Keane's...well, Roy Keane generally - or simply making them too damned scared to slack off lest they be subjected to his fabled 'hairdryer'.
Motivation alone though is not enough, and perhaps Ferguson's greatest achievement is managing to move with the times in a sport that has evolved greatly during his career. Rivals have occasionally threatened to usurp his position as the Premier League's top boss but have inevitably been found wanting. Kevin Keegan's wobbling voice on Sky Sports and Rafael Benitez's rant about dossiers of 'facts' concerning Ferguson's corrupt influence on the league are perhaps the most memorable examples of the psychological pitfalls of trying to compete with Sir Alex when it comes to mind games.
Just look at the two managers who have come closest to challenging his domination: Arséne Wenger and José Mourinho. Wenger's double-winning teams brought an attacking verve and pace that seemed to have done for Ferguson when he announced he would retire at the end of the 2001-02 season. Instead, revitalised by the challenge, he stayed in order to improve upon Wenger's system and take Manchester United to new heights, while Wenger's Arsenal went backwards.
Mourinho, along with Chelsea's sudden financial clout after the arrival of Roman Abramovich, also gave Fergie a headache - but again, it was only a brief one. Chelsea have turned to seven managers in as many years since Mourinho left, emphasising the difficulty of finding someone with the skills to take on the United boss. It's interesting to note that Mourinho is currently the bookies' favourite to replace Ferguson at Old Trafford, with many speculating that the timing of this decision has been influenced by the self-declared Special One's rumoured return to English football. Until today, everyone assumed he'd be returning to Stamford Bridge. Ferguson's abdication may have allowed him to strike a final blow at one of Man Utd's key rivals by instead opening the door for the Portuguese to succeed him, and thus deny the Blues the return of their most successful manager. We shall see.
Ultimately, Ferguson's final crowning achievement is his retirement itself. He leaves on a high, having captured his 13th Premier League title with arguably his weakest squad in twenty years, a tribute to his tactical and man-management ability. While Brian Clough scuffed his legacy slightly by holding onto power for too long at Nottingham Forest, and Wenger is in danger of doing the same after another trophy-less season at Arsenal, Ferguson could not have chosen a better moment to move upstairs. And with his stern, stoically gum-chewing face staring down from the director's box from next season onwards, his successor will have a hell of a job on their hands replacing him...
By Kier Wiater-Carnihan