Upstreaming multipath TCP

I dunno if this would make sense to implement in the OS kernel, but you could build this exact behavior into an application by having an anycast service that just returns the IP (and port?) you want the client to load balance to, followed by an MTCP connection to that service. One could probably make that into a client library and server daemon to make it easy to be integrated into any software that wanted to behave this way but the OS provides all the primitives necessary to have this work, and there probably isn't any benefit in abstracting that away into the kernel as opposed to having userspace control all the knobs and build on top.