In Cena's absence they're just going to over-push Mayonnaise Man instead.
The way I see it, WWE will continue to tease a Ryback and CM Punk match for the next couple of weeks, until the Raw before HIAC. If Cena has sufficiently recovered by then, they'll do an angle where he makes his grand return. If not, they'll swerve on us and name somebody else as CM Punk's replacement.
I say that, because I honestly don't think WWE wants to end Ryback's undefeated streak, and putting the title on him at this stage would be a huge gamble. Not to mention, that Ryback is hardly the deserving choice to end Punk's near, year-long reign. Don't get me wrong, ending the reign would give somebody a huge rub, but the truth is, only one wrestler can succeed Punk as WWE Champion, at this stage. That wrestler (if you can call him that, given his track record) is John Cena - that's how much WWE has failed at making big stars in the last couple of years.
Sure, you could have Orton come out of no where and defeat one of them for the WWE Championship. But the problem with that scenario, is that Orton has a fraction of the credibility that he had in Spring/Summer 2011. His character is incredibly stale, worse actually, it's stagnant. He has no where left to go in his current persona and no one left to feud with. A heel turn may solve this problem, but it won't make him a suitable contender for the WWE Championship.
Let's take a look at everybody who has fought for the WWE Championship in the last couple of years:
Credibility ruined by by booking following WWE Championship loss. Currently picking up the pieces in the mid card as Intercontinental Champion.
Brief flirtation with the main event went no where. Was suspended for breaking the wellness policy and that was the end of that. Now works a mid-card comedy gimmick.
Main event push went no where, thanks to safe booking. Hasn't really stumbled upon "that" gimmick or character quite yet. Building himself back up.
Alberto Del Rio:
Bombed as WWE Champion, was swiftly dethroned by John Cena and then booked in the typical cowardly heel role. Second WWE Championship run was also a failure. Spent most of the summer jobbing to Sheamus. Credibility is in pieces thanks to terrible booking.
Creative can't seem to decide on whether he is a heel or a face. Everybody knows that he can be beaten, and creative makes no efforts to actually push him as an unstoppable force when they characterise his as such - as evident by his numerous clean losses following his recent heel turn.
See Big Show.
Hell, I'd actually take a Ryback main event push/title run if WWE would actually put him over the likes of John Cena and Sheamus. That's how you make a new star, even the most protected of characters (Undertaker - outside of Wrestlemania) has done jobs and put over the most unlikeliest of performers in an effort to build new stars. Triple H put over Batista, Randy Orton, and Sheamus. The Rock put over Mick Foley, Kurt Angle, and Brock Lesnar.
There are so many examples...