If Canon releases such a high MP camera, then price will be one of the major factors accountable for its success. It does not look like an "upgrade" cam for 5DMKIII as it will appeal to a limited market (landscapes and studio shooters), so it will not be in any real direct competition with 5DMKIII.
Wait a second. I thought studio and landscape shooters represent the majority of the market, at least according to all the whiners on Canon Rumors 
No, the majority of whiners on Canon Rumors just want Canon to deliver actual improvements rather than the "same old" that is marginally better than what was previous.
i.e. They don't want a sensor in a camera that is almost identical in characteristics to one that is already 3.5 years old, they want a sensor that measurably has less bad attributes and measurably more good attributes.
If you look at Canon's sensor technology, the greatest improvement since they added Correlated Double-Sampling around a decade ago is their microlensing. Gapless microlenses were the most recent evolution on top of having microlenses at all. Since that "innovation" (I'm not even sure Canon was the first to use it), Canon has really cheated their way by. Fundamentally, Canon sensor tech is a decade old, if not older...where as the competition is using sensor tech that has been innovated throughout the last decade, with major improvements as recent as a couple years ago.
Most people used to think that the only real arena left for improvement in sensors was megapixels, and people were sick of "more megapixels." Canon did actually listen to their customers cry for "fewer, but better, megapixels and MOAR ISO!!" Canon's failure, though, was to see that the competition has been doing both...improving the quality of each pixel while concurrently increasing megapixels. I don't think people in general thought that was possible...the old anecdotes (which are still profusely regurgitated across the net even these days) about smaller pixels being worse pixels are wrong, and people are finally beginning to realize that. Canon, who holds the largest user base, seems to be stuck, stagnant, and I think people are finally realizing they have been for a LONG time. Now that its becoming known that we can have both MORE pixels while concurrently getting BETTER pixels, fewer and fewer photographers will be satisfied with Canon effectively standing still with their sensor technology.
The new demand is "More AND better megapixels!!", rather than "Better pixels at any cost, even if it means less megapixels." Personally, I think the demand is justified. Canon needs to get back into the game. They need to start innovating NEW technology, heat up the competition, and help drive prices down. That can only mean a win-win for the consumer...and being a consumer, I like my wins!