because they’re hard-coded to a DNS to avoid shifting IPs due to things like NAT

One of the many, many things we shoved into DNS was service discovery. It's not because of NAT, it's because we want to seamlessly support migrating from 1 server to 10 billions of them without reconfiguring anything.

The solution in indeed to migrate to IPv6, but that's because IPv6 multi-cast is actually usable. This time it's not because of NAT.