[Brightcolours]

Honestly I think Canon is more trapped than Nikon because the EOS Ms can't go FF ( I think at least ) and they will have a hard time to compete with MFT and Fuji. Nikon may go full throttle FF mirrorless at the CES already and thus compete with Sony.

Canon uses the same flange distance as the Sony E-mount. Canon also uses the same mount diameter as the Sony E-mount.

So in theory they can do the exact same thing Sony has done going from Nex to A7 series.

 

Besides that, NEX APS-C lenses are worthless for FE mount anyway, so it would not matter of Sony would have made a new mount for FE, as they need FF lenses for it anyhow.