The Foveon has great potential and great flaws.
To fix the latter in a reasonable time, imho, a great deal of resources are needed - the sort of resources maybe only Sony and Samsung have.
The good thing is that manufacturers are understanding that the Bayer sensors (and the mechanical mirrors/shutters) are the bottlenecks of modern cameras' performance. However the Foveon is not the only solution. There's another prototype of sensor (can't recall the name) that uses the energy of the photons to translate it into wavelength and then into color information.
Why not Canon? AFAIK Canon develops sensors in their own company. O.k., they are behind others in some specs + IQ under different circumstances. But in 2005 when I decided to buy a 20D Canon had a great advantage: It's sensor reproduced great color and detail - much better than other cameras from other brands and it was a Canon developed +produced sensor.
They have to do something revolutionary - evolutionary development of existing 18MPix sensors will not satisfy us and I think we will see some revolutionary sensor within 2 or 3 years.
Good remark about pixel quality instead of quantity. A 12 or 15 MPix FF sensor three layer sensor without antialiasing and high ISO sensitivity would be outstanding!