It's a tough one to call. On one hand its kind of lame to have Brock lose the Rumble and still get in (remember when it happened to Austin in 99), but if a RAW guy wins then they can do something else to get the Smackdown main event
(how about an 16 man tournament that starts on the first post-Rumble Smackdown and culminates at No Way Out, and have Brock win that one)
Then Jericho should win, but who would he fight at Mania?? Steiner?
The one that makes more booking sense is either RVD or Booker T winning the Rumbel in an upset and going on beat HHH for the RAW title clean at Mania (yeah fat chance), pushing one of them up into permanant main event status. Booker hasn't jobbed out to HHH that much so he's the more obvious one.
knowing the WWE, they'll have Big Show win the match with Brock and win th Rumble.