It's so early to think about the Royal Rumble winner and a Smackdown winner would be interesting (they really need to stop this brand business, there's no point any more). Randy Orton is my pick from Smackdown. CM Punk is my pick from Raw. If Cena isn't already champion again or dropped the belt for the umpteenth time I'd pick him.
There was talk about having the Royal Rumble winner use their title shot at Elimination Chamber...
The last time that happened (2008), we got stuck with a three way match between Triple H, Randy Orton and John Cena at Wrestlemania. To be fair though, it was cool that Orton got himself DQ'd in order to waste Cena's title shot

!
They are starting to return to the favourites winning the Royal Rumble again. Between 2006 and 2010 it was unpredictable. From what I can recall...
1998: Favourite was Steve Austin - Steve Austin won.
1999: Favourite was Steve Austin - Vince McMahon won.
2000: Favourite was The Rock - The Rock won.
2001: Favourite was Steve Austin - Steve Austin won.
2002: Favourite was Triple H - Triple H won.
2003: Favourite was Brock Lesnar - Brock Lesnar won.
2004: Favourite was Chris Benoit - Chris Benoit won.
2005: Favourite was Batista - Batista won.
2006: Favourite was Randy Orton - Rey Mysterio won.
2007: Favourite was Shawn Michaels - The Undertaker won.
2008: Favourite was Triple H - John Cena won.
2009: Favourite was Triple H - Randy Orton won.
2010: Favourite was Chris Jericho - Edge won.
2011: Favourite was Alberto Del Rio - Alberto Del Rio won.