Definitely. But then you need to define an envelope to mark where an individual message begins and ends (with UDP DNS, it's a single datagram; with TCP DNS, it

Definitely. But then you need to define an envelope to mark where an individual message begins and ends (with UDP DNS, it's a single datagram; with TCP DNS, it's the entirety of the transmission). There are infinite ways to do this, and countless many already specified in various standards (many of which are already implemented in browsers, which is surely the the primary application Google had in mind). HTTP provides one such envelope.