Possibly a full-frame geared more towards video and perhaps have the same sensor as the 1DX, but without all bells and whistles for stills?
Why in the world would they want to do that? The continuation of the 5d2 is a rumor, I'd rather think they'll try to squeeze as much money out of ambitious amateurs as possible (pros will buy a 5d3 or 1d anyway). This faster production cycle is where a manufacturer can make money from apart from selling a top quality lens once a decade.
Furthermore, the price of the body generally seems to be in the same range as 1-2 lenses of the same quality class - and current full frame bodies require very good (e.g. red ring) lenses.