The gist of what I'm getting from reading these forums is that what people want are the features and specs of the 5D3. They just don't want to pay the >$3K price tag for it.
But really: If Canon put out a 6D with the same 5D3 sensor and a slightly worse AF system/burst rate and priced it under $2K, who is going to pay the $1K+ premium for a 5D3?
This is of course true with any product but that doesnt mean the best busienss move is dropping the price provided there is a market who do want to buy the camera.
The D6 vs D600 situation seems to be more of a potential problem than the 5D3 vs D800 to me, with the latter the Canon did offer some clear advanatges(higher FPS, argubley superior video and AF) plus alot of users were already commited to there system anyway. With the former though the D600 seems to outspec the D6 across the board plus both are marketed towards users who do not have a commitment to a FF system.
Still I wouldnt rule out a very cheap 6D, Canon's tactics in the past have afterall been to price high at the pro end and low at the comsumer end. Specs wise the 6D seems "crippled" enough not to hurt 5D3 sales much and if the rumours for the 7D2 are correct(1DX level AF, 10 FPS) then I'd say both cameras at a similar price or perhaps even the 7D2 for a little more seem possible.