RAW: As far as the Raw roster goes, do we have 6 people who could be competing in an EC for the shot? We have: Jeff Hardy, Chris Jericho, Mr. Kennedy, Shawn Michaels, Triple H, and Umaga....what a coincidence, six......the only two other people in the main event possibility range are Randy Orton (champ) and Lashley (but I don't think they'd use him in place of one of the six above). As all those men are legitimate possibilities though some obviously couldn't be in the main event for Wrestlemania (Umaga, lol).
SMACKDOWN: Batista, Edge, Finlay, Khali, Mark Henry, Kane, Rey Mysterio, and the Undertaker. Knock one of them out for being the champ at the time leaves us with 7, and Henry isn't as likely as Khali though they both suck, so that's the six they'd most likely use.
There's a tricky situation with this, however. There's no way they're going to have the Undertaker win the rumble AND the championship at Wrestlemania two years in a row. However, they still need to have him win at 'Mania. If Undertaker goes into Wrestlemania as the champion, arguably the best option is to have Edge as the challenger, and since they're already in a feud, would they really waste that rumble win on him? Not very likely. So by that rationale, since we can almost definitively rule out Khali, Finlay, Mysterio, and Mark Henry...and most likely even Batista...it makes the most logical sense to have Edge win the championship in the triple threat match at Armageddon, retain against probably Batista at the Royal Rumble, have him screw the Undertaker out of a Royal Rumble win out of fear, then have the Undertaker win the Elimination Chamber. That'll give you your option to have him defeat Edge for the title at Wrestlemania.
BUT...(there's always a but, isn't there? lol)...to do that, that would mean that whoever wins the rumble can't challenge Edge. If that's the case, someone from the Raw side of things will be the most likely to win the rumble....here comes another paragraph haha...
Assuming Orton is the champ, I don't see them having Kennedy or Umaga win the rumble. Out of HHH, HBK, Jericho, or Hardy, all four are logical choices, but I'm going to go out on a limb here and say that the two least likely to win are HHH and Jericho. Jericho's being pushed against Orton right now and I think they'll have a rematch at the Royal Rumble, which will count him out, and he'll probably be involved in the Money in the Bank match instead at Wrestlemania or in a feud (Kennedy?). There are a lot of reasons I don't see HHH winning the rumble and I keep thinking of more as time goes by. For one, he's already won a rumble before, and its rare that someone wins more than once unless you're Stone Cold or HBK pretty much lol. Another reason is that it seems like HHH isn't building himself up for a feud with Orton. It appears he's already had that moment when he defeated him for the title and then lost it the same night. That, to me, was HHH's "Orton title feud". So we're left with HBK and Hardy. On one hand, you have Hardy, who seems to be in line for a serious push and it would do wonders for his career if he won the Royal Rumble. On the other hand, you have HBK. If I had to choose, he'd be the most likely option the WWE will take, for the following reasons: 1) Orton says he won't give Shawn another shot at the title and this is a roundabout way of forcing it. 2) HBK is totally cemented as a Wrestlemania show stealer and would give it his all. 3) If the WWE remembers the crowd reaction from last year's rumble, as it got down to HBK/Taker, everyone went apeshit, but the majority of the chants were actually for Michaels. If they want to capitalize on that, as well as pay homage to his two previous wins, he may very well be the final man or the second to last.
So overall, how do I think this will play out?
Royal Rumble winner = HBK or Jeff Hardy to challenge Orton
Elimination Chamber winner = Undertaker to challenge Edge
I think this is an absolutely great idea. When I saw that in the headlines, I got excited about the federation for the first time since I got a tease at No Mercy. I hope this is a long-term addition to WWE plans.