Yes, still using XP on many of my CNC's, with no problems whatsoever. Not hooked up to the internet, never will be.
I love not updating my stuff.
I'll still update hardware (and the Linux OS that runs it), but I'll still use the old Windows versions through VM. I don't use XP (never did personally like that OS version), but I'll run everything from Win 98 to Win 8.1 in a VM. Ironically, even production machines that were manufactured after Win 98 went EOL, they can still be driven by software that runs on Win 98.
In some instances, I do believe in upgrading and updating (especially hardware), but if something legacy can be preserved, especially via software (like using an older OS in a VM) and it still works on newer hardware, then that's where I start thinking about not updating.
The idea of having production rigs
needing to be connected to an outside network is not good in my opinion. And that's where instability can go from, either through malicious code or through a wonky update and Windows (Mac has had it's share of update issues and I have less sympathy for them as they have a tighter lock on hardware that runs their OS) does not have the best history of updates and the rolling release nature of Win 10 (which essentially makes the OS in perpetual beta stage in my opinion) just makes it worse. It can range from mild to mind blowing infuriating, especially when having to wait for an update to come from the software vendor to have the software in question work with the latest OS build version.