Well, the roster shakeups probably won't happen until after WM, and I highly doubt Lesnar drops the title before WM, so that pretty much stops any Raw guys from winning it. (Assuming Reigns/Lesnar is already pencilled in, because I think he'll just straight up issue the challenge. No need to piss the fans off again with a Rumble win.)
Don't see Orton getting it again. I would think Cena should be off the table too, especially if there's any chance he goes with Undertaker.
If it's someone on SD, AJ Styles seems like a reasonable bet (assuming he loses the title between now and Rumble).
The only other real possibilities I see currently would be Sami or Kevin, but that could change if they screw the SD team at Survivor Series, and somehow end up on Raw.
Otherwise, if it's not one of those 3 it would probably be someone unexpected that doesn't really need a title shot to sell a match (ex: If Lesnar starts something with Angle, and Angle wins the Rumble to face him at WM).