What they need to do is have Cena go back to the old rapper gimmick where he would actually come out rappin about his opponents. That was why he got to be so big in the first place, he has that charisma that all the real stars have. His promos are always better than average. And I'll be damned if he isn't one of the best at selling moves and injuries. So what if he isn't technically sound, WWE wants stories and storytellers, not wrestlers and wrestling.
They should turn him back into a heel, so the fans can boo all they want. Then when his movie comes out in the fall, they can have him be a face again. I know a big part of the Cena turning face was to promote his cd, and that came out a long time ago, so time to move on.