Canon is smart. They are market driven. If they see a demand, they release it. I don't think they 'demand' you see is real.
Possible, but Canon may not have technology to provide a quality high mpx in a cost effective manner. They did prototype a high mpx a couple of years back, but no words on it and whether or not it would be available. May be that project flopped and Canon is scrambling to compete against high mpx coming from Nikon and Sony.
Lets face it, high mpx is in demand, as proven by crazy demand for D800... its demand is almost solely due to its high mpx.