IPv4's class E network (240.0.0.0/4) contains 268 million addresses. Despite the advertisements for IPv6, claiming we have ran out of address space, this block ironically still claims to be "Reserved for future use". Why hasn't this block been freed up yet?

Of course, IPv6 should be promoted instead of freeing up more IPv4 addresses, but we've seen the address shortage coming for years. There has even been a time they weren't sure there was enough time to develop IPv6 before we would run out of addresses. Why didn't they free up this block already?

And is there any chance these addresses will be used in the future, like when IPv6 is fairly widely implemented but we still need IPv4 for backwards compatibility? It will be phased out regardless, but then ISPs don't have to employ NAT for IPv4 compatibility.