RFC8950 Lets You Run an IPv6-Only Backbone While Still Carrying IPv4
RFC8950: Announce IPv4 with an IPv6 next-hop
RFC8950 allows announcing IPv4 routes with IPv6 next-hops over MP-BGP, so a network core can be IPv6-only while edge devices still speak IPv4—no tunnels required. The author demonstrates a Container Lab topology with FRR where C1 and C2 exchange IPv4 traffic across an IPv6-only provider core. Supported by Juniper, Cisco, Nokia, Mikrotik, Huawei, BIRD, and FRR, this could make IPv4 an optional feature on backbone networks, much like 464XLAT did for mobile.
Thus what 464XLAT did to the mobile networks - this has the potential to do that for the backbone networks.