I don't see an issue. If a browser wants to create a websocket connection, it will always create a fresh connection and do a HTTP/1.1 upgrade. Because that's the only way how websockets are specified.
On the server side most things are handled in the low-level HTTP handlers. There (e.g. in Netty/Jetty and Co) one needs to care about ALPN negotiation, websocket upgrades and Co. But higher up (J2EE, express, etc) things are mostly about HTTP semantics, and there isn't any handling about "upgrade" or even the "Connection" field in general anymore.
Yes, the line between HTTP application semantics and HTTP/1.1 transport is very thing and nobody exactly knows where things start and end. But I'm still not convinced we need web sockets over HTTP/2, e.g. in order to allow upgrades in the application layer.
On the server side most things are handled in the low-level HTTP handlers. There (e.g. in Netty/Jetty and Co) one needs to care about ALPN negotiation, websocket upgrades and Co. But higher up (J2EE, express, etc) things are mostly about HTTP semantics, and there isn't any handling about "upgrade" or even the "Connection" field in general anymore.
Yes, the line between HTTP application semantics and HTTP/1.1 transport is very thing and nobody exactly knows where things start and end. But I'm still not convinced we need web sockets over HTTP/2, e.g. in order to allow upgrades in the application layer.