IPv6 is already backwards compatible though. There’s a /96 of the IPv6 space (i.e. 32 bit addresses) specifically for tunneling IPv4 traffic, and existing applications and IPv4 servers Just Work™ on IPv6 only networks, assuming the host operating system and routing infrastructure know about the 6to4 protocol and are willing to play ball.
IPv6 is already backwards compatible though. There’s a /96 of the IPv6 space (i.e. 32 bit addresses) specifically for tunneling IPv4 traffic, and existing applications and IPv4 servers Just Work™ on IPv6 only networks, assuming the host operating system and routing infrastructure know about the 6to4 protocol and are willing to play ball.
I learned a lot about it from this video: https://www.youtube.com/watch?v=e-oLBOL0rDE