Cena will eventually turn heel. If Hogan and Austin went heel cena definitely will. When? I have no clue but it'll happen. Whenever they find their next face of the company he's definitely turning.
My ideal heel turn would be during a wrestlemania match with taker ending the streak. Imagine cena turning.heel during the match and pinned taker? That will be the most heat EVER!
Top 10 all time favorites:
Stone Cold Steve Austin