Yes, everything has to be updated eventually, but going forward doesn't have to be this hard. A network and its hosts could start supporting ipv6 without changing anything else. Same addr and routes as before, same NAT, and no DNS6/DHCP6/etc, so very low effort and risk to turn it on. If a peer only supports v4, talk v4 to it for now.
Then once there's sufficient v6 adoption, you can disable v4 entirely and start using /40, /48, etc..
Then once there's sufficient v6 adoption, you can disable v4 entirely and start using /40, /48, etc..