There will be an impact felt when Messi leaves, but on the other hand, of course, things like this can still be minimized if they immediately move quickly to find other fresher players, but don't let the fans give high expectations because they are afraid the same thing will happen to Messi. can happen again to new players when it doesn't match their expectations.
Now Asensio is expected to be one of the strong candidates at PSG, hopefully he will not be damaged again in terms of fame by some irresponsible fans.
The impact might not be that big for PSG if the team can find a replacement that is no less good than Messi more quickly. However, during this break, almost all teams will try to find fresh and young players to replace the old players who have left the team. That's why all teams that have enough funds will move quickly to get the new players they want during a break like this, especially for teams like PSG who generally really need new players to have a better next season than the previous season.
As I said before this depends on how PSG find suitable players.
For a new player like Messi there won't be one I think because he is extraordinary but to find a player who matches PSG's vision it can still be done and of course this can still be found now with the finances and time that is still long enough I think they can do that though the pattern may still be the same because it only revolves around Mbappe when talking about PSG.