No, all they have to do is add a new manager and then put you on holiday permanently, that way you still remain in charge of Man Utd unless they sack you.
I would suggest doing something similar to the Pass the Parcel story but either have people pass the game over after each season or an odd number of people 3-5 passing it over every 3-5 months (this ensures everyone gets a fair share with the transfer windows but doing it your way where right at the beginning you each choose a team to manage and then holiday the managers not in use.
this could be an actually good idea for a competition in the challenge and scenarios forum if you make it so if a managers is sacked their out of the game, if you can get at least 12 people to be interested then you could set it up so you have 4 groups of 3 in the semis then the last 4 start a new game for the finals and a name for it - "Last Manager Standing"