The way the the ENS integration would work is the DNS request for vitalik.eth would end up at a Handshake Authoritative Name Server and then there are certain blacklisted top level domains (.onion, .tor, .i2p, .bit and a few others) where a client for that protocol is instantiated and then a request is sent out to the appropriate system and then the response would be formatted into a DNS query by the Handshake Name Server and sent back to the client.

Not implemented yet, but this is where one would implement it https://github.com/handshake-org/hsd/blob/master/lib/dns/ser... https://github.com/handshake-org/hnsd/blob/master/src/ns.c#L...