It would be great if Zidane were the coach of PSG, I think PSG has it all, it lacks a good captain, and Zidane will fill that lack. But now PSG is having many problems, player salaries need to be lowered, maybe they will cut that cost, meaning only keep 1 or 2 in the trio of Messi, Neymar, and Mbappe.
As for Messi, he is also under too much pressure when the press and fans criticize him, and blame him for past failures, I see that he is no longer attached to PSG. Maybe he will leave in the next transfer window, although PSG still wants to keep him.
The possibility is very small because Zidane has no plans to manage the club yet. It seems Zidane is very interested about the national team instead of club level which is actually good enough for him at the moment. In fact, in the last few seasons, he has been linked with several top Premier League teams, but in the end, all of them could not make it happen.
Some of PSG's top players like Messi, Neymar and Mbappe will leave in the end, that is an undeniable reality. Messi has been linked with a return to Barcelona, while Mbappe to Real Madrid or perhaps the Premier League. We will definitely find PSG in deep trouble without their star players if all of them leave next season.