I came across this interesting blog post from Rick Lewis who shares his experience switching from Fuji back to the Nikon D500
Why did I buy the D500 when I’ve shot Fuji exclusively since 2013? Well, there are a couple of reasons. The first, and major reason, is the speed of the camera. I missed the speed of my D4. The second reason is the size. I originally switched to Fuji cameras to go smaller, lighter, and cheaper, which they are. But, after shooting with an X-E2, X-T1 and X-Pro2, I’ve discovered they are just too small for me. In fact, I really use the X-T1 the least and I figured out why. It’s just too cramped, ergonomically for the way I shoot.
(He's still keeping one of his Fuji cameras, by the way)
There are a lot of posts, articles and so on out there about photographers switching from DSLRs to Mirrorless, but lately I've seen quite a few people switching back to DSLRs. I know of at least four people who I follow on Twitter who have switched back.