Man PSG just blew everyone out of the water this window.
I thought Man City could compete with them but it seems even they can't money wise.
They probably could pay 150M for Mbappe but they needed to rebuild their team (especially defense) much more than just investing all money into one or two players, especially forwards where they already have some great young talent. They overpaid for most of their signings this summer but that's expected. I still prefered what they did over PSG though.
Also, I think if City would try do to what PSG did with Neymar that FA would actually look into that deal and possibly sanction them if UEFA wouldn't do anything. Of course EPL would like to see a star like Neymar playing there (every league in the world would) but I don't think they would be as desperate to get him as Ligue 1.
Though in the long run I think this could also work against Ligue 1 if/when PSG will start to win the league for 20 or 30 points. People said years ago that La Liga is not interesting being a two team league but at least Barça and Madrid were usually competing until late in the season for the title to make things interesting. This won't happen in Ligue 1 with PSG bringing Neymar, Mbappe and possibly another top player or two and Monaco on the other hand losing half of their team. It would be hard for them to repeat last season even if they would keep everyone but now it's impossible they'll challenge PSG seriously. I hope I'm wrong but just don't see it happening.