It's an interesting situation, why have Canon not to date followed through with a higher MP Body ?? it's a little like "what's the meaning of life".
The decision to amalgamate the 1D/1Ds lines in the 1Dx was in my opinion a bad call on the future Market by Canon (albeit I think the 1Dx is a wonderful Camera Body), I just don't think their Marketing People clearly saw the Market need for a higher MP Camera (or they did, and simply weren't able to match technologies with Nikon/Sony), they got that wrong, and now they need some catch up time in designing a Sensor that approaches what the Market wants, and is comparable, better, than the Nikon 36MP sensor, and more recently the Sony 36MP sensor, and now, the Sony 50MP sensor that is finding it's way into the Haselblad, Phase One etc, and in particular the about to be released Pentax 645z.
The Pentax 645z is of huge interest to me, this is a 51MP CMOS Sensor, 3fps, high ISO Range, reasonable Lens availability, weather sealed Body, and not an inordinate amount of Money at less than 10k, that's a pretty good deal when compared to the Phase One IQ250 & Haselblad offerings of a similar type at 35k to 45k.
The Pentax will be limited as a Wildlife Camera @ 3fps, but the D800 which I have owned, and the Sony a7r which I do own, both operate at a Maximum 4fps, so not a huge difference there, even the 5DMK III is a limiting 6fps.
But the Pentax for Landscape, Portrait & Still Life should be a very interesting Camera at this price.
If, and it seems to be a huge if, Canon develop & drop a higher MP Body into the Market, it needs to be better all round than the Sony a7r & D800E, and hopefully it will be, there's no doubt in my mind that Canon have lost Market share due to these two Cameras from Sony & Nikon, and in loosing Market share to these two Bodies they loos Lens Market etc etc.
I believe Canon simply miss read the Market trend, and have paid a price, now they need to play catch up, and they need to do it with spades, that is, put into the Market a Body that pulls that Market share back from Nikon & Sony, from what I've seen over the Past few Years, I'm not convinced canon can or will be able to do that, I personally stay with Canon because of the Big Whites, there's very little difference in abilities between the D4s & the 1Dx, the D800/5DMK III, and Canon no longer have anything comparable to the Nikon D3x other than the 1DsMK III which isn't in the same league.
Of course this is all Navel contemplation, and ultimately useless, but it's fun at 0600 on my 3rd Espresso.