Im hoping that the wwe does what they did in the past and push a superstar using the rumble into either the mainevent status or at the very least to their first wwe title. Look at some past rumble winners, such as Yokozuna (won 1st title at mania and was main eventer for next year), the Rock (2000 was the Rock's year when Austin was out with injury, solidified himself as the top guy), Batista (given the mega push into both main eventer and wwe champion).
With that being said, there are a few guys that I would like to see win. The first is CM Punk, who I hope will be separated from the SES by this point. Punk is one of the best, if not in my opinion, the best all around worker in the wwe at this point. After cashing in MITB last year, Punk was a main eventer for probably 4-5 months, but then was relagated to upper mid-card. A rumble win and main event spot at WM I think will finally solidify Punk as a main event worker, especially with the number of guys who may not be around after this mania is over, or by next years (i.e. Taker, HHH, Edge, Jericho just to name a few I believe only have 1-2 years left).
The other guy who should win the rumble is the Miz. The Miz is the hottest thing right now and a rumble win followed by a main event at Mania could work. It may also be that its too early for this, and its possible the Miz just needs a high profile singles match at mania before this can happen. However with the talk of unifying the titles, it could work that Miz wins the rumble, goes against the SD! champion, wins that match and the title, and then later on in the night cashes in MITB against the raw champion and wins the other title. Something like that would just be AAAAWWWEEESSSSOOOMMMEEE!!!!