Bear in mind that there match was MOTY on Monday, when this was tweeted, and it looks quite possible.
Maybe, but odds are that Rock won't even be able to make Wrestlemania XXX fit into his already busy schedule (then again, he's been nicknamed the "hardest working man in Hollywood" for a reason, so if there's a way to make it happen, he will.)
Now that I think about it though, I probably wouldn't even mind if Rock/Cena III did happen. I wouldn't look forward to it and would much rather prefer to see Rock work with a different opponent but with the way things are shaping up for this year's Mania, as long as it wasn't for the WWE Title and as long as it didn't interfere with any other combination of matches that I want to see (and why would it?), such as Taker/Lesnar, Bryan/HHH and Punk/Orton (the latter likely being the one for the title), then I'm fine with it. Although it'd unfortunately be the headline again.
I doubt it's happening, though.