Short answer, I don't know. I don't know that they'll disappear, they are just so efficient.

That said, lattice is completely event-driven. The #on_event and #emit_event methods act as entry and exit points. As long as I can have string come and go between the server and client, HTTP2 would be fine.

This seems like a pretty good article covering it

https://www.infoq.com/articles/websocket-and-http2-coexist