I think the price thing applies more to second tier teams like Napoli or Sporting... For the top teams, I would say is his playing time. I think even if was cheap, none of Bayern, City, Chelsea, Liverpool, Real or Barcelona would start him. They might see some use for him from the bench but they wouldn't use him the way he wants to play now. It's only the ex English players like Keane and Sounness whose idea of football is to put 11 dudes out who can fight, run and hope for a 20+ goal striker that did not see what a problem he is if you are trying to build a team that can compete with the elite.
I agree with your second point! Really difficult to see Martial keeping his place with his inconsistency and injury record. But I think we will rotate between Sancho, Elanga, Martial, Rashford and Antony. Ronaldo to start maybe in certain games and to find a solution in January or something like that. Just difficult to see him ever starting a big game again.