Yes, if they want the Champions League title for the next few seasons, it will be difficult for PSG to make it happen. PSG must completely overhaul the squad and coach and that will take time. Therefore, Mbappe should be sold, maybe he also wants to chase the Champions League trophy with another team. I also believe that PSG will not develop if Mbappe is still around because the club has given him so much power that other people can't do anything, including the coach.
I don't know what underlies you to say if PSG should replace Luis Enrique at this time, because it seems that under Enrique, PSG is currently in good condition and also quite stable performance, replacing Enrique with another coach of course will only make PSG have to return to the initial process in building a strong team later, the change of coach is certainly not something that PSG should do at this time because indeed Enrique has managed to give a new color to PSG game, if you say overhauling the squad of course I strongly agree, although PSG currently have a qualified squad but they still need to improve next season especially in a defense that is indeed fragile, In addition, I see in some of the games played by PSG this season that their reserve squad instead has not been reliable.
Mbappe has left PSG and PSG should be able to get better players than him next season, so far Mbappe has a big ego and privileges at PSG, so it often causes divisions in the team, Mbappe ego is based on mis from management that gives him privileges so far that he feels the most powerful even above the coach.