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.
It may not be a huge market, but Hasselblad is the last man standing in MF at the moment, so if Canon moved in they could sweep up the MF pro digital market worldwide, at $20,000 per starter outfit - that is real $ and canon should not ignore it. I doubt it would be simply a digiback, but a whole camera solution.
I dont care for 800lb gorillas, but quite frankly I'd totally welcome it. Imagine some of Canons know-how in AF and sensor technology done in 645 format...