The gimmick/character of Cena's eventual TRUE replacement?
Hulk Hogan's Hulkamania
Perfect for Regan's 1980's and the craze for musclebound tough guys (e.g Arnie, Sly etc). Patriotic, clean living and larger than life. Suited an era filled with action shows such as the A-Team and bigger is better - MTV music videos, increasingly SFX ladded movies.
Steve Austin's Austin 3.16
Freely encouraging profanity, drinking alcohol and kicking ass. Violent and anti-authority. Perfect for the edgy late 90's, with edgy being the thing and it being cool to be bad. The Rock became on par, but it was Austin that exemplified the late 90's.
John Cena's CeNation
Started as a cocky rap/hip hop act - perfect for the early to mid 2000's when that pretty much ruled the music charts with Jay Z, 50 Cent, Snoop etc. The wigga factor fit with Eminem, who was perhaps the biggest artist in the world at that time. Morphed into a PC version, which fit with increasingly PC post 9/11 world. But still very 'urban' with the hustle, loyalty, respect schtick which suits the many middle class kids who like to think they're from the street!
So what do we have now?
Sheamus - Smiling Irish guy
Ryback - Tough HGH guy with one line
Del Rio - Rich mexican import
Orton - slow moving viper
Punk - pipe bomb maestro (easily the closest to having a cool 'gimmick')
Nah, has to have more depth relevant to pop culture if he's to genuinely replace CeNation