The conversation is ridiculously fast. * We can't not support IPv4. * IPv6 clients can connect to v4 only hosts. * Supporting IPv6 is nonzero additional work

The conversation is ridiculously fast. * We can't not support IPv4. * IPv6 clients can connect to v4 only hosts. * Supporting IPv6 is nonzero additional work. * The cost of v4 addresses is on the order of a deli sandwich. * (If not greenfield) We have a working v4 system right now and adding v6 support is entirely risk with no benefit. * (Meant negatively) v6 is substantially different. So we will forever be maintaining two sets of networking stacks that play by different rules.