PSG definitely need a score machine like Mbappe to keep their performance stable. Mbappe has the ability to score a lot of goals. But if match strategy and chemistry between players is not good, it is not possible to survive in a competitive platform like Champions League.
If Mbappe leaves the club in summer, which I think will happen no matter what PSG will do, the club will lose so much besides an exceptional striker. I think the whole team will suffer from Mbappe leaving them. They are so much less dangerous without him. Imagine you take him out of the team now, I think they wouldn't have the slightest chance in the Champions League as he is the player who can really decide a game within a blink of an eye. They would still win Ligue 1 as this is nothing special given how much quality they have in the team, but on the highest level Mbappe can't be replaced.
But I wonder, even though PSG has good finances or is the richest team in France but yes, it seems that PSG is not so successful in having and or getting young players with great potential. Because anyway, over time also young players with great potential like Mbappe will also leave and if Mbappe really leaves, then of course PSG will experience a decline in performance which may be very bad.
Because after all, so far PSG has only relied on Mbappe to become a goal machine and of course, if Mbappe leaves, it will take more time for PSG to get or have good performance only in Ligue 1. Because yes, we cannot consider too far about PSG in the Champions League because after all, only for competition in Ligue 1 also PSG still relies on Mbappe.
No player is bigger than the club, Kylian Mbappe leaves and nothing will drop down the performance of the club if the coach has the player's to win him games.
Don't forget that it's football played by eleven players, Mbappe will not reduce the performance are of the club. Berkham was important for Manchester United but he left and they coped. Same thing with Cristiano Ronaldo who left Manchester United and they did well. He left Real Madrid and they've also produced mlre two Ballon d'or winners.
The absence of Kylian Mbappe is just for the main time. Luis Enrique Is a good coach and he knows how to improvise and win big games. This first season is quite challenging for him.