Here's a wild thought. With the rumored amount of money that they throw at Floyd Mayweather and Kanye West, why don't they offer him that money for say, a 4 month segment instead? if the money offered is as much as filming, he gets a slightly less stressful schedule (no house shows of course) and is given a good storyline to work with, do you think he'll bite?
that would be exciting for any wrestling fan, but it won't have that big publicity as the two guys you mentioned. that would be amazing to see, but there's some problems for both sides.
-The Rock is trying to get as far away from wrestling as he can. That's why he's Dwayne Johnson now. So him returning to wrestling would just people remember "Oh yeah, he used to be a wrestler." The Rock might make some good money, sure. but he probably doesn't want to be typecast in that role of wrestler again by the mainstream media, because he's been doing extremely well making kids movies.
-It wouldn't have that big mainstream attention as say a Kanye West, Mayweather, or Shaq would. It would get the internet riled up, but you wouldn't be seeing the Rock's return on ESPN, TMZ, or The Soup. They'd want to get someone that's a huge media star, not a wrestling legend.
-What's there for the Rock to do? He probably wouldn't be booked to lose and be against a main eventer, so booking him wouldn't get anyone a rub. They'll just get the rights to say "I did - to the Rock."