If 10 years ago someone had told me that Sony would be competitive in the professional photography world, directly competing with the likes of Canon and Nikon, I would not have believed them. I think the most surprising thing is how they are doing this; not with the traditional DSLR, but instead with full-frame mirrorless interchangeable lens cameras.
Many professionals switched to Sony when they came out with the full-frame A7 mirrorless cameras, but many more did not. Switching systems when you are a professional is not usually a good idea, as the vast majority of your equipment investment is in your lenses not your camera bodies.
With the release of the new full-frame Sony Alpha A9 Mirrorless camera I can see many more professional photographers switching to the Sony system. With a 20 frames-per-second shooting rate without any blackout I can’t see any serious sports photographer not at least considering switching to the Sony system.
The A9 has a 24.2 megapixel full-frame sensor, an ISO range of 100-51200, 693 point autofocus system, 4K video recording, Dual media slots, and many many more features that would greatly appeal to a professional photographer. The A9 is not only feature full, but is also built to last. With its magnesium alloy body, and its dust/moisture resistant design, it should be able to take much abuse without breaking down.
I know if I was just starting out, deciding what system I would be using, Sony would be right up there with Canon and Nikon. If I was currently working as a professional sports photographer I would be seriously considering switching to Sony, with the release of the full-frame Sony Alpha A9 mirrorless camera.