I'm not so sure he'll like his football under Pep.
Obvs it sounds like its life changing money for him and generations of his family to come, but, he's always been the center of it all at Villa. Picked out in the youth teams as the main man. Always been allowed to express himself. Now he will have to do exactly as he's told or he won't even make the bench.
Henry has always said, it's Guardiola's way or the highway and it found it very hard to adapt. Only certain types of players/personalities can adapt to Pep's style of management. Is Grealish one of them? If his plan is to be a "Brummie Beckham" how is that going to sit with Pep? Probably worse than Beckham's fame sat with Ferguson.