He'd probably go to PSG if anywhere. They're the kind of club that'd force the manager to bend the knee to his whims.
No way Pep wants a 33 year old Messi who runs less than the goalkeeper and throws a tantrum when the coach tells him he's not above the team.
Messi has earned the right to do what he wants so to speak if he wants to leave. But if he goes to PSG I will be extremely disappointed. Anywhere else I wish him well. The club will be laughed at even more than now. I am also OK with getting 100m for him. If he goes for free it will be another failure for the club after Ronaldo commanded 100m at the same age.