Up until last Monday, I think it's fair to say that the general consensus among wrestling fans was that The Rock would never wrestle another match. His return on RAW this week, however, seemed to suggest that maybe, just maybe, that isn't the case.
I think it's also fair to say that the vast majority of fans would rate Rock-Cena as a dream match, and Rocky's promise to 'see' John Cena at WrestleMania seemed to suggest that it is a possibility. In my opinion, the match is a possibility, but at WrestleMania XXVIII in Miami, instead of this year in Atlanta, and here's the reason: what we already know about the matches at WrestleMania seem to rule it out.
Miz will almost certainly be WWE Champion going in to the event, and so a face is needed to challenge him, and it must be one of the competitors from the Elimination Chamber. The two other faces in the match are John Morrison and R-Truth, neither of whom are going to headline WWE's big show, at least not now. Barring a late entry to the match by Triple H, it will be Cena that will go on to face Miz. Given as well how Rock promised to 'see' both Miz and Cena at WrestleMania, a confrontation between all three is even more probable, perhaps with Rock as special guest referee for the match.
That doesn't, however, rule out a match between Cena and The Rock. It was announced recently that WrestleMania will take place in The Rock's home town, making an appearance from 'The Great One' and a Hall of Fame induction (if it doesn't happen for him this year) almost certain. The booking doesn't fit for Rock-Cena this year, but given the reaction The Rock received on his return, and the widespread calls for the match, there is no reason why they shouldn't wrestle next year. Indeed, WWE would be mad not to pay him a huge paycheck to wrestle one last time.
Here's how it could happen: WWE wont have Rock come in and beat Cena when he's their top babyface, but Rock wont be wrestling his final match, in his hometown, at WrestleMania, and losing. This means a Cena heel-turn is necessary. This could obviously happen at any point between now and WrestleMania if it is to happen, though given he's taking on the Miz, you would imagine it would be at the event rather than before. Cena would win the belt, and Rock would even raise his hand as if everything is cool between them before Cena attacks him, furious at the things Rock has said about him and all the attention he's taken away from "The Champ". Cue heel-turn and a year of everyone loving Cena as a heel. Sometime around the next Royal Rumble, the first Hall of Fame inductee is announced, and it's Miami's own, The Rock. This re-introduces him to TV and Cena comes out to confront him for, again, stealing his spotlight, and on the story would go from there...
Realistically, a one-on-one dream match between The Rock and John Cena wont happen this year, but for fans willing to wait until next year, they might get to see one for the ages, possibly even the biggest wrestling match ever, Rock vs Cena, "Icon vs Icon II".