To be honest, I really hope that Mbappe will stay at PSG because with him staying at PSG, of course Mbappe will learn a lot from star players like Messi and Neymar. Well, Mbappe may be going to Madrid which of course there are also many experienced star players but that will lead Mbappe to adapt again and of course it takes time. By the way, regarding the away game against Reims, I'm not just waiting for Messi's performance because I'm also waiting for Donnarumma's performance. Of the 3 games that have been played PSG still haven't kept a clean sheet, and I hope that if Donnarumma is played maybe PSG will get a clean sheet for the first time this season.
I totally agree that it is a pity he is most likely going to leave. I was trying to figure out why he would leave this year and not wait one more year. He could have gotten huge signing fee all for his own as his contract terminates. I guess he wants to leave because in his opinion he isn't as much in the limelight anymore with Messi's arrival. But I see that differently, I would say that Neymar, Messi and Mbappé could really set new standards as they all bring different qualities to the table that perfectly work hand in hand with each other.
I do not think that it is a pity, PSG had years to build around him, and they finally did that is true but the team wasn't really filled with too many stars, even Messi had stars like xavi, iniesta and countless others on his best year, Ronaldo had so many good players, Mbappe usually only had Neymar (and that is a big name I accept that) and others were just decent.
Plus, when a player wants to leave, you can't really make him stay for too long, dude was already an expensive layer when he came to PSG and if PSG declines to sell him, then they are accepting the fact that they will keep him for one more season for 160+ million, because that is how much they are missing out on, which means that is how much they could have made but didn't just for one season of him playing. All these getting together makes it basically obvious that Mbappe leaving is not a big deal, both parties are accepting the terms at this point to leaving after one more season.