Sir Alex Ferguson has become an institution at Manchester United and across British football. The thought of the great man not walking out at Old Trafford, not facing recurring FA charges for criticising referees and not constantly harassing the fourth official and squeezing out every minute of injury time possible.
Ferguson's legacy will be one of perpetual success and whenever he finally hangs up his suit and gives his vocal cords a rest his successor will face a monumental task in attempting to replicate his longevity and success.
Whether it's this year and going out on a potential Champions League triumph or whether the old man's got 10 more years in him, there are a number of high profile, highly successful managers who would be lined up to step into Ferguson's shoes.
So here are 10 potential candidates the Old Trafford hierarchy may be considering to replace their 20+ year veteran.
Mark Hughes is a United legend as well as having plenty of managerial experience and success in the Premier league.
He's had his taste of a 'big club' in his time at rivals Manchester City where he did a reasonable job that would make him a viable candidate.
The one question over Hughes would be if he could achieve major success at a major club, but apart from that he has a decent chance.
David Moyes is a great manager who's done a phenomenal job in his time at Everton.
However given a lack of funding in the transfer market compared to rivals for the top spots, there is a general feeling that Moyes has taken Everton as far as he can.
If Moyes were to make the step up he'd be a popular choice and there's no obvious reason why he couldn't succeed.
Solskjaer is a United legend, has a strong connection to the club and is a fan favourite, he'd make a popular choice.
After retirement the Norwegian stayed in Manchester taking charge of the reserves for two years before leaving to take a full managerial post in Molde.
He may be too inexperienced now but given a few more years, Solskjaer may be a strong possibility as a replacement.
It's been a rapid fall from grace for the former United assistant who achieved great success in partnership with Sir Alex Ferguson.
His experience and understanding of how operations work at Old Trafford would give him a facet in which he separates himself from the rest of the pack but the fact that that Queiroz has gone from manager of Portugal to top man in Iran in the space of three years since leaving Old Trafford is a worrying sign.
Queiroz's managerial nous may be his short-coming in being considered for the role.
He may be an outsider but in his time at United, few will have watched more of Ferguson and how he operates than the club's second eldest statesman.
The Welshman has shown composure and success on the pitch and may well replicate that off it.
Martin O'Neil has had a sustained break since leaving Aston Villa but could pick up his managerial career at the deep end with Manchester United.
No one has ever doubted O'Neil's managerial capabilities and his composure and hunger for success could well see him make a great replacement for Ferguson once he finally steps down.
If he's ready to return to football, Martin O'Neil could well land the job in a few years.
Blanc has assumed an incredibly difficult job in taking over a disenchanted French national team.
If in a couple of years Blanc can't replicate his recent club management success with Bordeaux nationally, he may well chose to return to the club scene with the United job a possibility.
As a former player Blanc would make a popular choice and could prove to be very successful.
Who would ever consider leaving Barcelona given their current footballing genius, the fact they have the undoubted best player in the world, and they have become the dominant force in European football today?
Well, supposedly Pep Guardiola is that man. Despite his long-standing Barca connections there continue to be doubts over the Spaniard's future and if he did decide to leave, there aren't many more enticing prospects than Manchester United.
If he wanted the job, there are few who could rival his claim.
Young, charismatic, little known at this point and manager of Porto: remind you of anyone?
Many have made reference to Villas Boas' resemblance to Jose Mourinho and if he can achieve similar success he'll be in hot demand for many clubs.
It may be slightly risky at this point but if it paid off, Villas Boas could be a spectacular success.
Mourinho has been having a torrid time in Madrid.
Mourinho's ego and self-importance has turned the once charismatic, media-friendly 'Special One' into a sour, bitter, vengeful man who can't handle the fact that he and his team aren't the centre of the footballing universe while Barcelona dominate both in Spain and Europe.
At United, Mourinho is bound to be the centre of attention once more and can be reunited with one of his greatest fans: the British media.
The prospect of trying to surpass Ferguson is sure to be one that temps the Portuguese manager as well as not being constantly undermined from above like he has been in both Madrid and previously at Chelsea.