Keith at NL has had predictions of a 6D for a while now. The 6D sounds reasonable, a FF body that sits between 7D and 5D MK III. Canon needs to stop producing the old 21mp sensors and standardize on the new and much improved 22mp sensor which already has been optomized for the DigicV processor.
I'd expect to see fewer bells and whistles, lower top ISO, fewer AF points and simpler AF without the separate Digic IV to run it. For many, it will be a huge step up, and much more affordable.
I even expect a touch screen, given the market these are aimed at. Hybrid AF like the T4i would be nice, but if it requires a different sensor, its not going to happen..