Fable 2 is going to be the highest selling RPG this gen (single platform)

[WiiStation360]

What could beat it?

FF XIII (PS3) definitely.
Dragon Quest X (Wii), definitely.
KH3, probably.
FFVs. XIII (PS3) possibly.
Fallout 3 (360), possibly.
Elder Scrolls 5, possibly.
Mass Effect 2 (360), doubtful.

KOTOR3, if it comes out.

Dragon Age Origins, no idea.
Super Mario RPG (Wii), oh yeah.