Hate him or hate him more, the guy is a great sports entertainer. Not necessarily the best wrestler, or our favorite character, but his spot as the face of a company that tries to look good to outsiders couldn't be filled better by anyone else.
He has taken the high pitched, juvenile chants of "Let's go, Cena!" and the machine-like response of "Cena sucks!" from the IWC just the same, but he still cuts a great promo, he can still have a good main event match (with the right opponent, of course) and it is clear he and Punk work well together.
It would be selling Cena short after his brilliant work in this feud to have him replaced with the next biggest face. He has a score to settle and for Cena to allow someone else to help fight his battle would not only be against the company's best interests, it would squash Cena's entire persona.
Remember at Money In The Bank 2011 when he lost to Punk after knocking out John Laurinaitis to ensure it was a fair fight? Cena has built his character on doing things himself and that doesn't always mean winning or losing or getting all the fans to cheer for him, but it definitely doesn't mean handing the reins of a great feud to Randy Orton.