IF Canon cannot make a camera that mechanically cannot shoot and gets lagged in electronics, like the Sony does, then I see no point for Canon to make a high end competitor to the A7RIII.
I have lots Canon bodies, and Sony bodies. If I need a "on-field" journalistic or fast pace ruin/gun response camera, my 5D is ALWAYS with me. The stupid glitchy Sony's while I love in studio AND while they always come with me as I cross my fingers they will do a miracle...They simply don't. SOmetimes it works out, and other times or most, I have to set it aside and let the Canon do its work.
Canon will surely need to keep the existing line of lenses.
Here is a list of the TOP Sony features I find GREAT!
Nothing new, but I rely on this stuff...
NO AA FILTER...I cannot stress this enough, as I have posted saying it here for OVER a decade!
Live view with effect on and off.
Focus peaking
Silent shooting
Tilting screen
Self Timer flexibility
Programmable buttons
Tether shooting to PhaseOne C1 is nice
Something the SOny CANNOT even relate or compete with is the viewfinder. The current 5D viewfinder is a WORLD apart in seeing your subjects that you just toss the Sony aside. Canon will need to work on something about this. (See "Wishes" below).
I would love to see a second thread mount hole on maybe the side of the body. I think cameras can evolve as multi point and use devices to help adapt to different straps or rigs people want to use, and it just makes it easier to have more than one mount point. (I often use a rig in studio with field monitor, vs then needing to disassemble things to use a strap. With 2 points I can leave the rig plate on and just add a strap to another thread.
*Wishes....
What would be revolutionary is a monocular design "eyepiece" Meaning the entire camera would cover the one eye like a goggle. SO its not a metal resting on your cheek, but a cushioned foam that isolates your eye., and the body is shaped like a goggle. A adaptable accessory would be a head strap/mount so you can use it hands free, or at least with remote. This would be an amazing evolution in a very pro level camera.