With windows I wouldn't put it past Microsoft to helpfully 'repair' it after any given update, similar with a lot of the privacy tweakers you can find. Then it becomes a monthly task after patch Tuesday to confirm your system is how you want it.

Recall is off by default, it's no more enabled on a clean install than Hyper-V. I think the idea is actually very good, but obviously the privacy concerns are not great. Microsoft has made a lot of changes from what I've seen to allow you to block it on x, y, z, etc.

It's off by default but still present on the system. You can remove it entirely via the "Turn Windows features on and off" dialog.

Probably no more than explorer.exe (i.e. internet explorer integration) can be torn out of windows.

explorer.exe is the graphical shell and file browser...

Yes, it can be removed via the "Turn Windows features on or off" dialog.

But removing the whole OS?

By not turning it ON.

Recall is opt-in.