Like Canon was horribly bashed 30 years ago when the EOS system was released. Lousy specs on the first couple of cameras etc. But the technology was there and it has taken others 30 years to start to catch up with the all electric mount. Look at the Nikon struggles for 30 years now in this area and finally have to change the mount which I will guess will not support most older lenses including the older AF type lenses. Yes they will likely mount with an adapter but so what? No matter what Canon comes out with it will most likely allow all features of all EF type lenses no matter how old the be 100% operational.Ha.....I hope you are right.
But, if history is any indicator, Canon will release a FF mirrorless that will be a massive internet disappointment, a spec sheet failure, and something that will be roasted like a luau pig in many a youtube video.
oh...and it will be used to take many wonderful pictures and outsell the Nikon/Sony offerings combined.