I think it's more likely that he'll receive a mixed reaction from the fans, something more along the lines of what we usually hear in regards to John Cena.
If he doesn't appear at WrestleMania XXX and shows up on Raw sometime between now and WrestleMania season next year, his response from fans MIGHT depend on why he's back and what he's doing. When his music hits, I could see him getting a good pop or something that's definitely mixed. After he lets fans know what his role is, it could range from a big pop to staying mixed to garnering a large amount of heat.
If he comes back next year to announce his WWE Hall of Fame induction, I think he'll get a strong pop, especially if he mixes a little humility in there along with his cache of catchphrases. If he's back to wrestle a match, I think their response could depend on who he's facing. If he announces he's going after the streak, for instance, I think it'll ultimately start out as a pop but his successive appearances to help build the match result in fans booing him. If he announces he's going after the title again, I think there's a very good possibility they'll boo him out of the building.