If Chipworks is right, then the jump to a high megapixel camera probably means a new sensor design approach:
"Given the geometric constraints of 0.5 µm design rules, Canon seems content to hang around the 21 Mp resolution for recent FF sensors through the use of shared pixels. Jumping to a higher resolution generally requires more advanced design rules and pixel sharing architecture...
It is worth noting that September 2012 marked the 10 year anniversary of Canon’s announcement of the world’s first CMOS FF sensor, the EOS 1Ds. While Chipworks didn’t analyze that camera, every Canon FF sensor analyzed since has used the same 0.5 µm design rules."
Let's hope it all works out.