I know people won't care, but I don't think we can get Messi. Beyond the sporting aspect, because I do think we are a romantic club full of History, one of the most iconic club in the world and the name Manchester United is something meaningful for almost any footballer in the world.
However, Messi doesn't speak a word of English. Yes, we have players who could talk with him: Mata, Pogba, De Gea, ... not sure if the Portuguese speaking lads can somehow learn a bit Spanish, but basically, it's a tough situation. And Ole wouldn't even be able to converse normally with Messi.
Compared to that, Pep can directly instruct Messi without translations. And they know each others. That might work well at City.
But we know that Ole is old school and the United he envision is one where the team speaks English, and bonds in English. So I don't know how this will work out.
Of course, for someone as unique as Lionel Messi, maybe we should try to accommodate, if even given a chance. Which we probably won't be anyway so we can move on!