Mbappe will probably stay if those two leaves, and considering how much they are paying him, he will probably stay without a doubt. I think getting new players for those positions and better team all around for them could become a lot better. A team that is basically 5-4-1 in different shaping, is what they are doing and they could definitely make that work if they get younger and faster players.
Messi and Neymar have 54 scorer points taken together. I wouldn't exactly call them unreliable for that matter and Messi hasn't been unreliable at all. Neymar yes, due to his injuries.
Mbappe would be nuts if he doesn't leave PSG soon. What is a player like Mbappe looking for in Paris except for money? This guy is such a great soccer player and you think he should spend his career in Ligue 1? Someone like Haaland immediately ruled out PSG. He didn't even consider it for a second. He wants to play the best all the time, not just in some semifinal of the Champions League: MBappe is throwing away his career and the only thing saving it is that he is playing for the French national team and can win World Cups and European Championships. That is something Haaland can probably never do, which is a pity with Norway. But still, he wouldn't just go to Paris for the money. Mbappe in the Premier League would be amazing, seeing him play against all those top teams every weekend.
The problem is that you barely know how strong you really are until you meet the best teams in Europe. When you play in Ligue 1 and you beat Troyes 3-1, how do you know whether you can beat Manchester City? But when Manchester City beats Arsenal, Liverpool, Chelsea, Tottenham, Manchester United, can they know whether they are weak or strong?
I don't like the idea that PSG gets pushed by a sheikh to win the Champions League. Because they buy the strongest players with a lot of money who then play sub their abilities for a whole season except for a couple of games in the Champions League.
Wouldn't rather want to see Mbappe play against the best teams in the Premier League? Isn't it more fun when he destroys a team like Manchester United instead of Troyes? What happens if a sheikh decides to push Dinamo Zagreb and buys Haaland, Vinicius Junior, some of the best and then you can watch the whole season the HNL if you want to see how the best players in the world win against HNK Gorica.