At this point, the state of IPv6 support in Tor is already pretty good. IPv4-only clients can access IPv6-only sites, and IPv6-only clients can access IPv4-only

At this point, the state of IPv6 support in Tor is already pretty good. IPv4-only clients can access IPv6-only sites, and IPv6-only clients can access IPv4-only sites. No configuration is needed. It actually makes Tor an useful 4to6 bridge. Also, hosting Onion Service on a pure IPv6 network is possible and should be reachable by everyone, opening up some possibilities (just like Onion Service behind a NAT opens up possibilities).