This comes up every time IPv6 is discussed. Any change to IPv4 to extend the IP space (eg your example) would require a breaking change to the specification. S

This comes up every time IPv6 is discussed. Any change to IPv4 to extend the IP space (eg your example) would require a breaking change to the specification. So this would require changing every router on the planet to support it. You're also focusing on how the IP address is written when that doesn't really matter. Changing the format isn't dragging out IP adoption.