PSG's strength will be clearly different next season as a result of Mbappe's departure to Real Madrid, but to just become champions again in Ligue1 I also think that it won't be that difficult for PSG because considering that the other teams in Ligue1 are also not experiencing such significant developments. However, for the UCL competition, PSG certainly won't be able to do much if there are no more reliable players in their squad next season. Moreover, other teams that will also enter the UCL next season, such as Real Madrid, already have quite an extraordinary line-up of players next season.
PSG this season failed to retain their star players despite having offered salaries and also luxury, but Mbappe desire to find new adventures and also of course the Champions League trophy made him reject all offers given by PSG, currently Mbappe has officially become a Madrid player and next season of course we will see a new era of Madrid in La Liga and also the Champions League,
Mbappe departure will indeed have a significant impact on PSG's strength next season, and I think it will make PSG's performance decline slightly, because indeed so far PSG has relied too much on Mbappe to achieve every victory, so far PSG has dominated Ligue 1 very easily and they won the Ligue 1 title without strong enough resistance from other teams so, Mbappe departure will not be felt too much in Ligue 1 as they still have a strong squad for domestic competition.
But it's different when playing in the Champions League, although they may still be able to compete but still PSG must find a solution to overcome the loss of Mbappe who is their star player so far and of course PSG must strengthen the team as a whole to be able to win their first Champions League trophy next season, next season Madrid will of course again be a strong candidate to return to become Champions League champions next season after they have a squad which is really quite perfect at this time.