Of course, many things will not be the same as before. PSG, which had a lot of power with Messi and Neymar, entered a much more difficult process with their separation. The biggest trump card they have right now is Mbappe. Together with him, they have spent this year in the best way and are the biggest candidates for the League 1 championship. If they become champions at the end of this year, I'm sure it will be different in the next transfer period. I guess they will make the sensational transfers next year.
We can see in PSG's last game, apart from 70% possession and a landslide victory over Lyon away, PSG's defense deserves criticism and must be fixed immediately. Letting Lyon create 19 kicks and 8 that are on target is not a good thing for PSG if they want to win the League and the UCL league. I remember PSG's defeat in the UCL when they were against Real Madrid 3-1 when PSG had won 1-0 first? Benzema's 2 goals as far as I know were due to collective errors in the back area. PSG must improve to improve the defense sector this season to be able to compete in Ligue 1 and in the UCL league.
I may have a different point of view from you, I don't think the departure of Messi and Neymar will affect PSG's strength this season because Mbappe is already there. We can see that when he is not playing, PSG's performance looks 180° different. Even with so many star players like Messi and Neymar it will make it irregular when in the game.