I see Bryan being a tremendous part of WWE's future, but he won't be replacing Cena. There has to be (and probably will continue to be) at least one babyface who has that big, hulking look. It's a look that goes back to the 1920's (if not before) and has been exploited by every wrestling promotion since. Having those guys, however, you also have to have other standard archetype characters: the charismatic heel (Punk, Orton), the quicker, littler guys (Bryan, Ziggler), and others.
Bryan will be a big guy in the main event as one of those littler guys (like HBK was...it's not an accident that HHH himself referenced Shawn when talking about Bryan, which got brought into a Cena promo about the match) who is capable of carrying the title. Other guys who had that capability in recent memory include Jericho, Guerrero, and Benoit (Who?). The question then becomes who fills the large, hulking babyface role. Ryback, Langston, and Axel (who's built more along the lines of HHH than Hogan) are all guys who, in the future, if they can put it all together, could fill a similar role to John Cena.
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