Guidetti should never come back to City. Personally if I were him, I'd stay at Feyernord for as long as I could. He is a legend there. Has gotten a bit arrogant though. Now he doesn't celebrate as much with his teammates when he scores anymore.
I watched this video of all his goals somewhere, and the transformation was interesting. From the ecstasy of scoring a penalty early, to celebrating with teammates. Now he pushes them off so he can do the hulk hogan "I can hear my Name" or the love sign. By the last few goals, fewer teammates were running over to celebrate with him, almost as if to say, "we know you have something planned, and we don't want to get in the way of you doing you!"
And not to diss an academy player, he is scoring a lot, but this isn't excess talent producing results. He just seems to be on a hot streak. Anyway either way he is a god over there, he can never be loved here like that, coz he will be at best a parttime starter. That is his talent level.
And players (especially strikers) simply don't get "Pre transfer request Tevez" kind of love, from parttime work. Their is a reason why Dzeko is not a god here.
Guidetti is like Tevez was 2 years ago over there. They love him, and he loves it that they love him.
I hope he stays there. And this has nothing to do with the fact that I know he is not good enough :P