While that's true, and I agree with you, it's a headache no matter who is involved because even Mbappe will favor going to a club with a guarantee of a starting position.
Further, when it comes to Mbappe, you have the additional problem of Monaco similar being obstinate and not letting him go. This is likely because:
1. A number of Monaco stars are already shaping up to exit this summer. Bakayoko has all but asked to leave. Fabinho is talking about other clubs and also expressed a desire to exit. Sidibe, Lemar and Mendy have all been linked to other clubs, City included.
2. Monaco won't sell half their team even in a standard season, let alone one that has been successful. Even an average side likely wouldn't part with 2-3 of their best players in one window, but a team successful domestically and abroad will be unlikely to shed more than 1-2.
3. Mbappe is the jewel in the crown, their most popular player and with the highest upside by a measure. He's worth a massive payout now and a massive payout next season too. Losing Bakayoko and Fabinho would sting, but keeping Mbappe would be seen as a victory and would be retailed as such, without any decrease in his value.
Aubameyang, Sanchez and Dybala are all proven, top-tier goal scorers. So is Sergio Aguero. The problem with Kun is that he's lost the plot a bit this season and hasn't been doing the business. He missed another tap in on 87 minutes against Liverpool and even regular punters in the stands that I spoke to admitted we couldn't rely on him any more. Would Auba, Sanchez or Dybala have the same problems? Maybe, but there's always Jesus anyway.
Agreed 100%, though I do think that potentially Kelechi is out one way or another. He just hasn't seemed to find Pep's favor and he'll be desperate for the game time to impress.