There are lots of stories here on Fstoppers about photographers, including fellow writers, who are giving up their current camera brand and changing it for a different one. If you feel you're late for the party, you're not alone.
That's for the eager folks. Brand switching is a subjective decision. If you don't have a technically sound reason for that, you don't have to do the switch.
Am I Switching Anytime Soon?
No. I'm not late for the party at all, because I've never felt the need to attend it. The type of work I do goes well with the camera and lenses I currently have. In my photography, I'm working on commercial portraiture projects. For my style, it requires a camera in full manual mode that can capture a portrait of a person, most of the time using strobes for lighting. I can do that with pretty much any camera that's built for professional use (mainly from materials' perspective).
In my opinion, there are only two factors for changing the camera brand or the camera model.
Whatever the reason for buying a new camera is, it may be cheaper to get one from a different brand. This can be dictated by the need for a second camera or your current one already falling apart. Before making that decision, you need to do the math and see if that will be good for your wallet relative to your current camera and lenses' investment.
Insufficiency for a Certain Type of Work
Some people switch to a different camera, because some of the characteristics of their current gear are not as good as other brand's ones. If you base your decision solely on that ground, you will end up spiraling down the rabbits hole. After next year's NAB event, you'll find cameras with yet better overall characteristics.
Why is blindly comparing camera features not the right approach? Because you may not need that feature. I started my business with a Canon 40D, which, back then, was already a discontinued model. It had bad noise above ISO 800 and was only 10 megapixels. Why did it work for me? The price was right, the build quality was right. Most of my work was lit with strobes, and I used the lowest native ISO. The file size was enough for my clients' needs: publishing on the web and 8 by 10 prints in magazines.
Let's have another example on the high price point end: medium format cameras. Most people are drooling over the quality of a Hasselblad or a Phase One. However, if you're a sports photographer and can afford such gear, that will be the worst choice of your career. ISO performance is not that great. The cameras are very slow, because of the large files they create. You won't be able to use them in burst mode. The bodies are heavy, and they usually don't shoot video. Can you say they're worse than a mirrorless or a Nikon D5? No. It's just not the type of camera for every job.
Next time you see someone switching camera brands, don't get anxious. They have their own style and their own needs. You walk your own path.