The bigger question is how long before Canon leapfrogs Sony.
Why would Canon want to leap backward? I do not think Sony has yet to achieve Canon-like levels of environmental/weather-sealing, and the ability to detect, and synchronize exposures, with flickering ambient light, for consistent exposures and WB. What about Sony professional service/support? Canon, Nikon, Sony, Fuji, and plenty of other cameras can make the images I want, and until my recent retirement, could make the evidentiary images my duty required.
When I was shooting images for official purposes, Canon had the edge, due to weather-sealing, including a high-quality macro lens with I.S. and weather-sealing, plus a superior flash system, including a macro Ring Lite. Let’s remember that weather-sealing is not just about the weather, but other things that could enter the system, and contaminate or damage the interior, and it is convenient to be able to use water to clean contaminants from the exterior of the equipment.
Now that I am retired, and birds/wildlife/action have become more important, Nikon has the edge, due to the newest AF technology. I did not “switch” from Canon, but added new D500 and then D5 cameras. Nikon had already been my “secondary” system, for several years, anyway. (My wife has been a serious Nikon DSLR shooter longer than I have been a serious photographer; we do not normally share camera bodies, but do share lenses and flash.)
To get my attention, Sony is going to have to improve weather-sealing, further improve the selection of lenses, and start making adult-sized camera bodies, or at least position the controls so that adult-sized fingers, wearing gloves, can work the controls quickly and effectively.
Yes, Sony sensors can make wonderful images, but there is so much more to photography than than the sensor.
I do not hate Sony, though I remember Sony’s sudden exit from the notebook computer market, so wonder if Sony might suddenly lose interest in cameras, too. I really liked my amazingly compact, yet capable, Sony notebook computer, and had wanted to upgrade within the Sony system. Had Sony not exited the computer market, I might well have chosen Sony to be my ILC system, because Sony was “my” brand. I had bought a Sony DSC-H20 camera, to match my Sony notebook computer. Yes, I was a Sony customer, and felt abandoned.
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I wore a police badge and pistol, and made evidentiary images at night, incorporating elements of portrait, macro, still life, landscape, architecture, and PJ. (Retired January 2018.) I enjoy using both Canons and Nikons.