When I got home from work Friday I decided to pop in some Lesnar matches and one of them happened to be against Cena from Backlash 2003 (the night The Rock faced off against Goldberg). The match wasn't very good, but my God... Cena was a fantastic heel back then.
My one and only problem with Cena is that he comes off as such a kiss ass during his promos. "I missed hearing "Cena Sucks" so much, blah blah blah." How fucking gay is that? He should shoot on those blueberries that boo him.
I guarantee if Cena were to turn heel, all these 'smarks' would be all over his dick just like before. It ALWAYS happened with The Rock, and I'm positive it'd happen with Cena.
Before somebody says, "Yeah, but... Cena is WWE's main money getter, why would WWE ever turn him heel?" I'll tell you why: There's this unbelievable babyface for him to feud with that would be a license to print money, and his name is Jeff Hardy. A heel John Cena vs. a babyface Jeff Hardy would do wonders for WWE. But it would have to be a long-term feud like Austin vs. Bret, and not just some brush off bullshit like WWE has done since 2001. They're always in such a rush to get feuds over with and have the champ feud with someone else. That's ridiculous.
Also, if Cena were to turn heel, whoever he's feuding with merchandise would go up, and I think he'd draw more ratings and pay-per-view buys as a heel as well. People underestimate how much a great heel can truly draw, and WWE has always had that problem. Vince believes that the superhero is the one that draws the crowd, but Roddy Piper deserves as much credit as Hogan gets for Wrestlemania. If Hogan was facing off against somebody the fans didn't hate, then the show wouldn't have drawn half as much as it did.