İlkay Gündoğan's desire to leave is nothing but that he wants more minutes to play and at Man City the competition is very fierce and it is possible that İlkay Gündoğan will not get full minutes of play, that is very natural for a player.
İlkay Gündoğan's performance is still quite good so it's only natural that many top European teams want him.
but on the other hand I think that İlkay Gündoğan's departure will not have a big effect on the Manchester CIty team, Pep Guardiola's team already has a very strong character, even if several players leave, it will not have a big effect on the team's performance.
I remember in interview when Pep said he is not going to keep anybody who doesn't want to stay. So İlkay Gündoğan is free to leave or stay. But then I support his decision to want to leave because in my estimation City didn't show any seriousness in keeping. If city is not going to give him enough playing time because of his age, then he should leave. And I hope to God that he doesn't go to Arsenal. He should go to Barcelona or some club abroad.