hogans turn worked so well because as we found out years later, he is much more like Hollywood than Hulkamania in real life.
cena is genuinely a good guy, i do not think he could portray the cocky, cheating heel.
the only "heel" mentality that would work for him is the "i carried the company on my back for 7 years, and i still get boo'ed, cena sucks, etc." but then he would be a crybaby like bret hart. again, i do not think he could play that role well.
beisdes, everyone who vince wants to dislike cena already does, and has for about 4 years.
i cheer for the heels, always have, always will. that is why i love cena as the face, and as the wwe champ.
he is the all american boy. clean shaven, no tats, good looking, jacked, speaks well in public, great ambassador.
nothing better than cena getting beat for the title at a ppv by a heel after a nice, long feud ala money in the bank 2011.