My bet is that it will be a 22.1 mpix
I think that's pretty unlikely. The Nikon D800 is pushing up against diffraction limits, and this would go well beyond that because of the APS-C sensor size. It is simply not practical to go much higher than the 7D in terms of APS-C sensors.
Also, the data handling requirements of this would require faster processors and path handling, which I admit is a possibility, but Canon will not wish to cannibalise the higher end market.
If this MP is achievable in APS-C I would expect to see it in a 7D2, if anywhere, but I suspect the image quality would be pants due to noise and diffraction, particularly in the non-L lenses likely to be in use at the lower end of the market.