This really hasn't been fleshed out at all, it's more like: "Well, we're built on Cap'n Proto, it'd be really easy to expose it for applications to use. But is it useful?"
Arguably Cap'n Proto RPC might be an interesting way for a Worker running on Cloudflare to talk to a back-end service, or to a service running in a container (if/when we support containers). Today you mostly have to use HTTP for this (which has its drawbacks) or raw TCP (which requires bringing your own protocol parser to run in "userspace").
That said there's obviously a much stronger case to make for supporting gRPC or other protocols that are more widely used.
Arguably Cap'n Proto RPC might be an interesting way for a Worker running on Cloudflare to talk to a back-end service, or to a service running in a container (if/when we support containers). Today you mostly have to use HTTP for this (which has its drawbacks) or raw TCP (which requires bringing your own protocol parser to run in "userspace").
That said there's obviously a much stronger case to make for supporting gRPC or other protocols that are more widely used.