Losing Mbappe would cost PSG really a lot by the way. He is like their everything at the moment. In his absence I don't know how consistent and powerful PSG can be. They have made a good transfers for the future maybe but these new players will need to take their time to adapt and improve their skills to create a solid team.

In case of Mbappe's leaving maybe PSG would look for a solid replacement for him. But for now I don't know who they would go for. Maybe Haaland? Because his release clause is expected to be active by this year so we never know what PSG will do after that.