The challenge, though, is that WebSockets are simply a protocol for communication–they do not define the structure itself. All the goodness that came with REST (structure, human readability, self-description) is abandoned for the sake of efficiency. This is why Wordnik created SwaggerSocket!
I don’t know if REST is the right term here (the quick start is more RPC than REST) but I definitely think there’s a future for APIs to use something like WebSockets to handle asynchronous bidirectional communication. WebHooks are not well-suited for super high-volume scenarios and that could be a place WebSockets shines.