And so quickly? Then is what you misread mine, 2 years from now a year from now, not tomorrow, and even if it is tomorrow, it is not sudden, he has being a face for 7 freaking years, that is not quickly.
I do think in the Aftermath, I see the benefits of his turning, maybe you don0't even know about, people will turn with him, a lot of his older haters used to be Cena fans when he was a heel, and if a kid follows like some of us used to do, you don't turn on him, you turn with him.
When Stone Cold turned, a lot of people kept cheering, same happened to Hogan, and Sorry but Cena is not on that league yet, but he could in a few years, heel turn or not.
The only thing I say is don't be as closed as your post make you seem to be, the turn can benefit everyone some day, not now and not tomorrow but some day and if you thing that is something sudden, then the one mistaken is you. John Cena probably won't turn in along time,but when the time is right, the possibilities of it happening are very real.