grpc-web is almost exactly what I just described to you, though ironically it could add more complexity (because it's an extra framework that imposes the framework's way of doing things on you), but it should probably do everything we just talked about as well lol
http://www.grpc.io/blog/pubsub
or maybe not quite, since I just found this too:
https://github.com/tmc/grpc-websocket-proxy
Well, I've surely been looking for an excuse to put it to work. Are you also in the beta?