I'm glad Cena went over Corbin at SummerSlam. Corbin has regressed this year and taken a step backwards. All his feuds have came up short and haven't been that great. I don't mind Cena clean every now and then, but he can't put everyone over because it wouldn't mean anything.
I also don't even want to see Cena turn heel. His promos and overall character has improved tremendously over the last couple of years, and I don't mind seeing him continue this until he retires. There were several opportunities to turn Cena heel in the past, but I think that ship has sailed long ago.