To summarize the last 25 pages of rumor on this body:
It looks to be a 7D body (pretty much exact same button layout), but with a strange viewfinder bulge instead of pop-up flash (which would indicate FF), yet the viewfinder opening itself does not look like a classic FF one (rather, a crop or perhaps APS-H..?). However, some Smart persona noticed that the 1D X (FF) also has a visible viewfinder cutout, though it seems to be wider than the one in this picture. So this being a FF body with a 7D button layout (like a 5D mk3 with layout makeover) is not impossible; but it could also be APS-H.
If were APS-C, perhaps the bulge indicates a new nifty feature. IR AF assist, or IR flash trigger?
- A new "rate" button; its placement suggests that it's to rate pictures with, not to change framerate.
- Dual card slot (icon seen at the top LCD in some picture).
- The original source shows pictures of two bodies, the 1D X and this new "mystery body" (probably 5D mk3).
- Bird photographed authentic and correct subspecies to the supposed location of this picture taken. (Helmeted Guineafowl)
- Missing "creative auto" mode on mode dial.
(akiskev's image, nicely done)