Re: "We have now run out of IPv4 addresses"
If IPv6 hadn't been artificially complicated in an engineer's fevered dream, there would have been no problem to go to IPv6. Just tack on four more bytes, and consider that the existing IPv4 space was simply 127.0.0.0.x.x.x.x and that would have worked fine and everyone would have understood.
You mean, somethung like:
Addresses in this group consist of an 80-bit prefix of zeros, the next 16 bits are ones, and the remaining, least-significant 32 bits contain the IPv4 address. For example, ::ffff:192.0.2.128 represents the IPv4 address 192.0.2.128.
It's a shame they didn't implement such a thing.... https://www.google.com/search?q=ipv4-mapped+ipv6+address
Other than the longer IP addresses, and the fact they can be written in hex, and using NDP instead of arp, there isn't really much difference.