Then Bayern would have to persuade the player to sign a contract renewal - and if not decide if they want to keep a player who does not want to renew and does not seem to feel well. If the situation between the club and the player is still fine and the club does not have doubts about the performance in the next season they probably will hold the player for another year if the contract still is longer than a year - if the contract would run out the following year they probably would sell...
I think the question is first a question between City and the player. If the wish of the player to leave is too big (and I think that might have to do with Sane's playing time in recent time with Guardiola) and there is doubts about his performances the next season and if that might influence the player value, too - then it might be ok to let him go if the transfer sum is acceptable.
As Bayern fan I do not really know if Sane matches to the club and the other players. The right mentality is a big thing with the Bayern fans. Ribery was loved from the first moment somehow whereas Robben had to earn the love of the fans and it only really started when he worked hard for the defense, too. Sane is the guy that comes to a meeting of the German national team (that wanted to show more nearness to the fans and "being down to earthness") in an expensive designer outfit and a 18.000 EUR backpack. Maybe he just does not care, maybe he is just too stupid - or maybe he just loves to show off too much - none is really good.
