The hardware for CNC machines is still being made, and the controller doesn't really "wear out". It's not getting constant updates and it only really runs one program. The software could be fixed, sure, just need to find someone who can get the Fanuc environment to run on a Mazak Fabrigear 300. And then they need to do the same thing for this Mazak Fabrigear 400, no, it doesnt use the same control environment as the 300. And the Haas mill. And the Amada F0-3015 flat laser. And the Cincinnati press brake. And the Strippit turret punch.

The issue isn't that it can't be done, the issue is you'd have to write a new control environment for each type of machine, and most machine shops don't have the capital to throw at each machine to solve a problem that doesn't really affect them at all.