To keep things on topic, the point is that a 20Mp sensor even with new ultra L lenses is at the absolute limit of 35mm lens optical resolution. Canon are not stupid, and can see where its headed - they *have* to produce an MF (larger sensor) solution if they want to go beyond 20Mp in any meaningful way.
Success does not require success in every niche, including extremely small high end ones. Instead, some niches are way too small for an 800lb gorilla to bother with, even if such a niche keeps a few far smaller operations like Hasselblad-Imacon, Mamiya/Cosmo and Rollei going --- just barely. Adding MF would at best add about an extra 0.1% share of the DSLR market to the 50-60% share that Canon has already. This is like saying that survival for Toyota, GM, or Ford requires them to start competing in the sector now dominated by the likes of Ferrari, Lamborghini, Bugatti or Rolls-Royce.
Canon apparently realized this decades ago when it abandoned medium format (TLR's) to concentrate on the smaller and vastly more profitable 35mm format, and I see no reason that it would reverse direction now, with MF having a vastly smaller market share and far less profit potential than it did when Canon left it.
The argument that Canon needs to go to new, larger format lenses in order to get beyond lens resolution limits of 35mm format makes no sense to me: Canon's lenses had those same resolution limits with film, and it was never a reason for canon to upsize to MF then, so why would it be now?
In other words, where is the evidence that more than a tiny fraction of camera buyers want more resolution than Canon's current lenses can give them enough to bear the burdens of a larger format?