I don't deny the fact that PSG may change dramatically after Mbappe leaves, the only question is in which direction, because it's quite possible that they may not develop adequate tactics for the new season without Mbappe and then their results will be lame at least at the beginning of the season. Although they have no competitors in Ligue 1 you could say
Ligue One becomes an important league when we have the Frenchman in the league, he was popular enough to make it entertaining and competitive, we love watching Kylian Mbappe playing for Paris Saint-Germain, carrying the team's burdens on his shoulders. Kylian Mbappe was the main star in PSG and have dominated everything the club, his prowess and incredible ability made him to be formed. Paris Saint-Germain can survive without the critical aides from Kylian Mbappe who happens to be in Real Madrid jersey. Luis Enrique knows the challenges he faces and working towards resolving them becomes smooth for him.
PSG remain the favorites in Ligue 1 after Mbappe's departure. Luis Enrique will likely have more freedom in managing his team because he won't feel pressured by just one particular player.