Why? It would be to the benefit of relatively few and be an enormous technical problem for decades for everyone. If we did this, the IPv4 addresses would run out again after a few months at most, leaving us all in the same position we are in today, but also with a huge technical problem of fixing all the old devices which had these now-repurposed networks hardcoded.

If you are fine with doing the work of obsoleting old equipment, then just start using IPv6.

240/4 can be hijacked/used as private IP space currently by a lot of devices. I think Windows might be the hold out. But for internal routing and IoT it’s very useful. Can never be used as publicly routable space.

I’d like to see it added to the official list of private space alongside RFC1918.

No. It will take 10 years for everyone to update their router configuration/software to treat the new “formely-reserved” addresses as global unicast. There’s no point in doing that whatsoever. That effort would be spent much better by adopting IPv6.

Holy cow. Didn’t realize there is an entire /4 reserved for future use.