I think you're going to start seeing a lot more use of anycast with ipv6 instead of a long list of ipv4 servers.
There are problems which can be solved by using multiple A records, which you cannot solve by using anycast. If a connection to one of the IPs fail, the client can try another. If you think anycast will give you automatic failover, you are mistaken. In order for that to work you'd need to reliably detect when one replica goes down and ensure no traffic goes there. Not going to work.
Even the HE anycast DNS sometimes suffers from that problem. The anycast address will go to the closest DNS server, which might not respond. I actually put the unicast address of another of the servers as secondary.
Another problem with anycast is that as traffic does get shifted around between replicas, all TCP connections will break. Solving that is complicated.
Of course it is possible that Google uses different loadbalancing mechanisms for IPv4 and IPv6, but any loadbalancing method that works with one can also be done with the other.
But right now I think each of those IPv4 addresses handle more traffic than the IPv6 address.