I feel that is one plan WWE has had in place for a while that has much less chance of changing than any other idea.
I think WWE wants to make a big splash, and that splash is having a Hollywood leading man as the current world champion as it builds to its biggest event ever.
In terms of The Rock returning full time, I don't expect to see him working many matches as the champion. I could see him appearing regularly, but I don't think he will have a match on television each week the way we see CM Punk or Sheamus currently do.
It would be interesting to see if The Rock works dark matches at WWE events, both to help get attendance from those shows up to make them more profitable and allowing him to get some work in.
Last year, I heard he was working out with R-Truth and The Miz privately as he prepared for the Survivor Series 2011 tag match against them. I think this was done because of The Rock's busy schedule and he wanted to get loose in the ring.
If he has the time open in his schedule to commit to WWE, might as well have him get loose while making money off of him in front of the live crowd.
However, after WrestleMania 29, I do think he will disappear back to Hollywood.