An interesting idea, but QUIC / HTTP/3 also avoids the extra RTT for TLS negotiation by bundling it with the connection handshake and in a less janky way than this. I don't see a good reason for a server or browser developer to implement this when QUIC exists.
HTTP/3 seems to offer all these benefits already... <i>And</i> seems to be simpler and more compatible... And doesn't require a new DNS field which will surely trip up plenty of middleboxes...
This reminds me of the noise protocol which lets you communicate securely with a single round trip.<p><a href="http://www.noiseprotocol.org/noise.html#zero-rtt-and-noise-protocols" rel="nofollow">http://www.noiseprotocol.org/noise.html#zero-rtt-and-noise-p...</a>