I think we're always going to have that: there will always be That One Software that doesn't work on Linux, and you need to keep another OS around just to run it. I was able to get rid of Windows everywhere in my home except for one gaming PC, where I keep it around just for Fortnite, because of Epic's insistence on using their nasty kernel-level anti-cheat. So I keep that one machine around isolated from the rest of my network, for the sole purpose of playing one game.

I'm now in the process of un-Appleing my home too, and it's going pretty well, but I know I'll need to keep a single Mac somewhere in the corner of my garage in case I need to use Xcode to build an iOS app or something.