48-bit is probably not enough; 64-bit was even considered in early IPv6 drafts and it was discarded because it wasn't quite convenient enough for all the routin

48-bit is probably not enough; 64-bit was even considered in early IPv6 drafts and it was discarded because it wasn't quite convenient enough for all the routing magic that was intended to happen. The syntax change of addresses: makes it easy for parsers to determine the difference between a v4 and v6 address. It basically hasn't affected adoption (do you think 6 octets would have changed that?)