Hogan is not the example to use here, Bob Backlund is. It's one thing to just carry the company like those two did, but Cena arguably has put more work and dedication into it. He's already made headlines for his work with the Make-A-Wish foundation. And nobody is a better spokesman for the company like he is. Making him a heel now while he's still fairly young and strong would be a mistake for those reasons. Do it when he's almost out to pasture and forgotten about when so many others will eventually pass him by like Reigns is being designed to do now.