When Sir Alex finally calls it a day at Old Trafford the United hierarchy will face the unenviable task of trying to replace the enigmatic Scot.
You can guarantee David Gill will have no shortage of applicants to sift through but just who, if anyone, can replace Ferguson?
There are not too many candidates in my mind that will be able to follow Fergie's legacy at the Theatre of Dreams, but former Chelsea boss Jose Mourinho stands out from the rest.
Mourinho has consistently been linked with the United post and when Ferguson's son, Darren, currently in charge of Peterborough, revealed he believed his father could retire at the end of next season if the club overhaul Liverpool's overall Premier League title successes, the speculation once again surfaced.
The self-proclaimed 'Special One' is by no means expecting Fergie to retire in the near future, but he revealed it would take a brave man to turn down the chance to manage United.
"Which is the manager that says no? Nobody can say no," said Mourinho. "Manchester United belongs to a small group of clubs from around the world where nobody can say no.
"But first of all I don't believe in 2010 he is leaving - I don't believe.
"I think year after year he is the same, he's exactly the same person; healthy, happy, so I don't see a reason for him to quit.
"And in a very fair way, I hope he still goes. I hope he still goes on, because he's good."
Mourinho's right- the 67-year-old has not shown any signs of slowing down and his hunger for success is still great, but when he does decide to bring the curtain down on his managerial reign, Mourinho will surely be on the short-list to replace him.
The Inter Milan boss has the ability to cope with huge pressure and turn big-name players into a strong unit. His tactical knowledge is also first class and his dealings with the media have been legendary.
So when Fergie does step aside I think Mourinho will be the ideal man to replace him and continue the success enjoyed by Ferguson.
By Phil Tomlinson