Using IPv6 on the backend is already something ISPs do in many CG-NAT scenarios. This is exactly what DS-Lite does, though that does require a CG-NAT terminatio

Using IPv6 on the backend is already something ISPs do in many CG-NAT scenarios. This is exactly what DS-Lite does, though that does require a CG-NAT termination solution (then again, if you're an ISP you probably have a box that supports doing that lying around somewhere anyway). For new networks larger than 10/8 going IPv6 native makes sense I suppose, but for existing networks I'd expect migrations to move towards DS-Lite and similar techniques rather than 464XLAT; it's a less messy solution, and from what I can tell it's also more often present in CPEs.