If Sane had matured like you said and accepted Peps authority 100% then sure I wouldn't see much of a reason to not have him back. However I feel his whole attitude was probably why he's not really pushed on. You see players like Foden who know they are great, want to play all the time but just keep listening and working hard. Sane always let that frustration bubble up and there was probably times off the field that we didn't see.
Sane is brilliant but he's the only one standing in his way and I hope he realises it before he becomes another Mario Balotelli