I admit that benching Arda Güler at Real might hinder his development. But there are better loan options for him soon. Anyway, I think he should stay, and i belive he will shine later once he gets a proper club to be loaned. He still has enough time to develop himself. There's no need to rush.
Arda Güler already stated before that he wasn't intending to join back Fenerbahçe soon. Loan or permanent move, it doesn't matter. Therefore I just expect those rumours to stay as they are.
Yeah he is benched by Ancelotti most of the time and it is frustrating for any young and talented player who is very eager to play more and prove themselves. But Real Madrid is full of stars so he has no choice other than being patient.
If he was playing for Barcelona for example then maybe he could play much longer. I'm not saying it to underestimate their squad, don't get me wrong. I'm just trying to say that Barcelona gives more chances to youngsters.