Whether started in the build-up to WrestleMania 32, or towards the end of 2016 (with a view to a 'Mania 33 showdown), Cena vs. Roman Reigns must surely happen on the grandest stage of all at some point. Like a potential Undertaker vs. Cena feud, this storyline wouldn't exactly be the most difficult to write. Reigns, desperate to prove himself a future all-time great, aims for the company's big dog - ie. Big Match John. This would be a huge torch-passing situation, a match which really solidifies Roman's status as one of the next big faces of WWE's future. Although that might sound like many fans' idea of their worst nightmare, there's one way this feud can benefit Reigns (and the future of the company) immensely. It's unlikely that WWE would go down the heel-turn route, but having Roman cheat to beat Cena would really rescue his floundering character - particularly if he engaged in a vicious post-match beatdown to really solidify his status as a mean ass-kicker.