#2 - One last big-fat contract
The career of Leo Messi is fast approaching its end. He might be playing for another 4-5 seasons max before he hangs his boots.
He isn't the world highest paid player right now and though Barcelona have promised to make him, it seems unlikely with this board. Manchester City, however, have everything to do it.
Messi is not the sort of a player who is bound to turn into a manager. Once he retires, one does not see him becoming a coach or a manager.
He would have to depend on his commercial deals but before that, he would want to earn how much ever possible to make things easier after he hangs his boots.
The Citizens will definitely make him the World's highest paid player ever and with him moving to the Premier League, he would only end up getting more commercial deals.
Moreover, unlike clubs in Spain, Premier League clubs do not demand a percentage of what the player earns in Image rights. It'll only result in Messi earning more money!