The more and more I think about it, the more it seems like this is going to happen (especially with what happened on Raw this week)...
The top candidates to win the Royal Rumble:
1. Batista - Jumps ship over to Raw, setting up the Smackdown elimination chamber, where Undertaker wins to face Edge, giving HHH his spot against Flair, where HHH turns heel by beating him, since he's been wanting to turn heel for a while and he was booed during the Raw match with Flair.
2. Undertaker - The only way this happens is if they want HHH to win the elimination chamber to face Orton at Wrestlemania, but then it gives Flair nobody to lose to, unless he's perfectly fine with losing to HBK, who needs some sort of match at Wrestlemania.
Because of option #2's weird standing with Flair, that's why I can't see HHH winning this Royal Rumble and why they gave him the out, saying he's not even in it. From the next show of Raw onward, HHH can be blaming Flair for costing him his Royal Rumble shot, leading up to the heel turn at Wrestlemania when he beats him (and then eventually has a feud with Cena, as he wanted that...ugh). When Cena comes back, Raw's roster will be filled up with main event stars (Cena, HHH, HBK, Hardy, Jericho, JBL, Umaga, Orton, Kennedy, and possibly Batista) so the draft comes right afterwards and they "clean house", shipping probably Umaga and Jericho off to Smackdown in exchange for two midcard guys. Uneven face/heel ratio turns HHH to a heel, giving him programs to work with Cena, HBK, Hardy, and Batista, who also have JBL, Kennedy, and Orton to work with. 4 vs 4.
So all in all, I think we're seeing Batista win this Royal Rumble, which really, really sucks lol. Hopefully, if they go this route, they figure out a way for Edge to screw the Undertaker, instead of just having Batista toss him over the top rope. Personally, I'd like the other 3 in the final four of the Royal Rumble to be HBK, Undertaker (screwed elimination by Edge and the Edgeheads), and either Kane/Kennedy/MVP/Morrison. HBK needs to come in second again, cause everyone goes nuts when that happens lol plus it'd be "a Raw guy vs a Smackdown guy" which they like to do.