As for Canon being able to enter mirrorless FF on their convenience, I do not agree. If they were to enter today they would have lens disadvantage in comparison to Sony, outside the few low quality STM models Canon lens lineup us not that good for CDAF focusing (they do not have focus motors optimized for efficient small correction), that is the stuff that makes mirrorless magic happen like Eye-AF, superb accuracy and makes mirrorless AF tick in low light. The necessity of CDAF in mirrorless is caused by PDAF sensel size related physics (small on-sensor PDAF sensels not sensitive/accurate enough to drive these lenses efficiently in all the same conditions where huge cross-type mirror-PDAF AF sensels can) so it is not gonna change overnight. This in addition to the fact that Canon struggles to produce up to date sensors even to their mirror-cameras, with mirrorless sensor development is even more crucial.
IMO Canon and Nikon are now in position where Nokia (I'm from Finland so I had 1st row seat to follow their fall) was several (7-8) years ago. They have market leadership, but they present very little innovation, seem arrogant and are ignoring that trends are clearly pointing to direction they are not moving into.