Would be interesting to see who wins the Rumble this year. They seem to really be pushing Alberto Del Rio hard so I wouldn't be surprised if its him. However, I also wouldn't be surprised for Trips to come in at #40 and eliminates Sheamus or Cena to win it since its been speculated that his return has been "imminent" for several weeks now. It will almost certainly happen at the Rumble.
The only problem here is that his next logical match is to continue the feud with Sheamus. For that to happen they would need to somehow find a way to put the belt on him between now and WM to make it work, and I don't see that happening (Sheamus is awesome when utilized properly and they really need to get the belt on him again soon, although Miz is a great champ and its refreshing for the belt not to be on Orton/Cena for a change. They need to keep it away from those two as long as possible).
Wade Barrett, Del Rio, Cena, (the loser of Orton/Miz), and Trips are all wild cards this year, as I could see WWE pushing any one of those guys into a headline match at WM. Hard to tell, but you can almost bank on at least 3 of the final 4 participants being in that list. Nobody else has a legitimate shot IMO of winning it.