Personally, I don't see much money in Rock vs. Orton. I've little doubt that they could have a good match together but, at the end of the day, the WWE has used The Rock to go up against guys who are THE top draws in the company. I'm not saying that Orton doesn't draw or hasn't been a draw for WWE, it'd be ludicrous to do so. Maybe it's just me, but the notion of Rock vs. Orton just doesn't sound all that exciting.
IF, IF, IF The Rock was to come back as a wrestler for WrestleMania XXX, the best way for The Rock to be used, in my opinion, is against someone who is wildly popular or to elevate someone else on the roster. There was talk of The Rock vs. Brock Lesnar at WM XXX for a while but if rumors are correct, it's going to be Taker vs. Lesnar at the big show. Speaking of Taker, one scenario that some have talked about is Taker vs. Rock but it doesn't sound all that appealing to me. Maybe it's because we saw them go at it so many times during the Attitude Era that the notion of a couple of Attitude Era megastar just doesn't get me going.
Personally, I think WWE could build a legit money match between The Rock & Daniel Bryan if they kept Bryan as a babyface. The Rock did deliver a Rock Bottom to Daniel Bryan on Raw 1,000 last year and Bryan seeking payback for that...well, that's half the build right there. The other half is to employ a tactic that's being used with Orton in which The Rock is someone who won the genetic lottery, has a great look, is "pretty", comes from a great wrestling family & legacy that he was able to use as a means of success, etc. Bryan could portray The Rock as someone who had success handed to him in WWE, that he's someone who "sold out" wrestling to go make movies, how all the talk about "never going away again" is just hollow promises he's made, how he's only back to be in the spotlight, to promote his movies and to collect a big paycheck from WWE while doing it, etc. I honestly think that The Rock could be cast as a heel in such a feud, even without a heel turn, as his popularity among some fans isn't what it once was. The novelty of The Rock coming back a handful of times in order to wrestle a big match at WM, while retaining that massive level of popularity, has worn off on some people. The few times The Rock's name has been mentioned by other wrestlers in promos since WM has resulted in quite a few boos among the fans, especially the night after WrestleMania.
However, it's not likely that The Rock will be at WM XXX as a wrestler if the various reports are correct. WWE allegedly informed the company that makes all their merchandise not to make anymore Rock stuff until at least 2015, so he might not even be back at all in 2014. Plus, there's talk of him being one of the top choices to play The Terminator in the 2015 reboot, the filming of which is said to be going on right in the middle of WM season next year. The Rock's signed a deal to star in a WWE Studios production of The Fall Guy based on the 1980s TV show. I've little doubt that he'll make appearances on WWE television to promote the film sometime, but I don't expect it to be until late next year or even sometime in 2015. He's also set to appear in the next Fast & Furious movie, the filming of which will probably start in the relatively near future since it's release date is July 11, 2014.
So yeah, I doubt Rock vs. Orton will happen. It's looking extremely unlikely that he'll be coming back to WWE next year and if he comes back in 2015, I don't expect him to wrestle. The Rock's movie career is far too lucrative at this point for him to risk suffering severe injuries working as a pro wrestler.