Cena probably won't retire for a long time, but I doubt he'll be the face of the company for much longer. Just a feeling I have but looking at how things always work themselves out, Cena has been on top for over 7 years, which is about as long as someone like Hogan was on top back in the 80's/90's before he went stale. And he was bigger than Cena, obviously. I think before long (say a couple of years), someone will pop up or someone on the current roster will get seriously pushed and end up being the next huge babyface to carry the company. Who that will be, no idea.