I heard a rumour (possible spoiler)

[wrestling_god]

WWE is considering running an angle following the Royal Rumble where the winner of the Royal Rumble match decides whether he wants to face the RAW Champion or Smackdown Champion at WrestleMania. This will leave the door open for Goldberg to win the Rumble and go on to face Smackdown Champion Brock Lesnar, but also keeps things flexible.
One option if WWE does not go ahead with the Goldberg/Brock Lesnar match is to have a Smackdown star, possibly John Cena, win the Rumble and then go on to feud with the RAW Champion (likely Triple H) for WrestleMania XX. WWE is considering moving Cena to RAW permanently and making him the brand's top face following WMXX since RAW will not have a major face then (assuming Goldberg does not sign a new deal with WWE).

There is also talk of Chris Benoit winning the Rumble and going on the face Triple H as well (more likely). These are the current plans that WWE is looking at.