Nikon has the D3S and the D3X. Two FF pro cameras one with low resolution but fast frame rate, and one with high resolution and slower frame rate.
I would expect to see the same from Canon if the 1D is replaced with a FF version and fast frame rate.
Right now, the 1D MK IV has the same photosite density as a 27 mp FF camera, if they made the sensor FF and did not change the photosite density, it would be 27 mp. This may be easiest to do, since the design is mostly done, it merely needs to be extended to cover a larger piece of silicone. Undoubtedly, there are other challenges, like reading the data fast enough to get high frame rates.
It is likely the ability to move data fast enough that is a key piece of technology needed to move the 10 FPS 1D series to FF and 27 mp.