There is a strong implication in the current WWE 'Authority' storyline that the John Cena heel turn is imminent. The current world champion must turn heel if he is to become the main man in WWE and have the support of Triple H and Stephanie McMahon. Every storyline needs a payoff, and the payoff of the Authority story could be the revealing of John Cena as a heel corporate champion. It is clear in the story that Hunter and Steph are not fully convinced with current "face of the company" Randy Orton. The fact is, in reality Cena legitimately is "the face of the company" and McMahon's choice as corporate champion. The "Authority" storyline could be the blending of reality into story - which has always proved to be the most engaging storytelling device in the WWE.
Cena must turn heel in order to fully exploit the "authority" storyline. Orton is a poor choice as corporate champion, he isn't the clean cut suck up that Cena is. Orton is more of a lone wolf style badass. Cena is the perfect man to play Orton's current act as the hated golden boy of the company. Stephanie McMahon has legitimately been Cena's biggest cheer leader backstage in the last decade, the current storyline could reveal all of that support. Cena could join Stephanie in the Authority storyline to thank her for her support. There have been several teases that this heel turn is coming. At Survivor Series Cena was filmed talking to Stephanie and Hunter backstage. Later in the same event he stood alongside the heel bosses before entering the ring to hold his title up to Orton. Hunter and Steph were not stood with Orton, they were stood with Cena. The next night on Raw it was the same case again, Hunter and Stephanie supported Cena and didn't support Orton.
The heel turn must happen if Cena really is going to beat Orton and unify the titles. The win alone would place him in Orton's current position. As the champion he would automatically be representing the Authority. He could naturally become a heel. The sensible conclusion to the current Authority storyline of disappointment in Orton is that Cena becomes Champion and ignites the television product by becoming a huge heel star who can work a heated Wrestlemania 30 match with probable Royal Rumble winner Daniel Bryan.