I am not sure if Pep would be able to turn his personality around. I mean Pogba is not a bad player, I would love to see him in any team, when he plays for real he is not bad at all.
But, he has personality issues, usually doesn't get along well with his teammates, and has issues with teams he plays for and wants to constantly leave as well. Remember Balotelli? I mean he was such a talented player when he played, moved as high as City if I am not wrong, he was super talented, but he had personality issues and that is why I believe that he is nowhere to be found these days. Pogba may not be at that level, but he is not far off neither if you ask me.
With age, Pogba has changed quite a lot and now there are practically no scandals around him (at least I don’t remember anything serious in recent years). The fact that he has a difficult character is normal, in a highly competitive sport it cannot be otherwise. Guardiola has worked with such players (Ibrahimovic, for example, even if it was not the best cooperation) so if necessary, they will work together without problems.