After losing Lionel Messi who did not renew his contract, PSG has potential will loss their star player Mbappe next season after announcing not to renew his contract which will end next season in 2024. Seems difficult for PSG right now, if not sell Mbappe they will loss great opportunity to earn above 100 million euros due Mbappe contract expiry on June 2024. But one side they if want get transfer fees has to sell Mbappe and seems the era or PSG have been over after leaving by Lionel Messi and Mbappe.
Left Neymar not rumor yet will leave PSG or not, he has linked with Manchester United but not official announce yet for Neymar leave PSG because he still injury right now and absent many games with PSG in this season.
However, PSG's situation without Messi and Mbappe is unlikely to be as fragile as you might think. PSG could buy many of their target players if they wanted, but they also have to be careful because they will also be threatened by FFP. I don't think PSG will lose Neymar and Mbappe for free, so they will sell them to whoever makes the same offer they have at the moment.
Real Madrid, Manchester City and Chelsea are reportedly interested in signing him from PSG, but it looks like Real Madrid are the frontrunners compared to the other two teams I mentioned. Mbappe is a player that suitable for Real Madrid well after Benzema left, so I hope Real Madrid can complete that as soon as possible.