They should wake up because losing Mbappe is really a big problem, it's not same like losing Neymar and Messi where they're replaceable. If PSG didn't sign any great player, their goal should be win Ligue 1 since there's a high chance they might not become a champion in this season.
Lyon have successfully sign 7 players, 4 of them are from Premier League. I wouldn't be surprised if Lyon will finish in the top 3 considering they can comeback from relegation zone to rank 6 in the last season.
That is, the loss of Messi and Neymar was not significant at all for PSG, but the loss of Mbappe was a disaster? A little strange logic, in fact, the loss of Messi was also significant, it immediately affected their attack. I don’t think they were very worried about Neymar, because they wanted to get rid of him for a long time, the salary list only improved from this, and they were not very happy with his results. Mbappe's importance was only that he was the only striker left from this great trio in the team, but his departure was expected, and PSG just need to find a replacement for him, he is not the only striker who can score goals.
My thoughts also don't match the logic that OP conveyed, because it's like considering Mbappe to be the most important player compared to the other two players who were at Paris Saint Germain. Yes, I will not deny that Mbappe is a player who has contributed a lot to the team's play, but that doesn't mean he is everything that will determine the fate of Paris Saint Germain in the future.
Personally I would have an even squad rather than just having one or two star players. Even though the squad they have is not that luxurious, by having an even squad that can work well together, the team will be more solid than just having one or two star players. Meanwhile, we know that Paris Saint German always has star players, but in terms of play their teamwork is still lacking, so this makes them always have difficulties when facing teams that are at the same level as them.