Kind of, yeah. ActionCable is just the plumbing though. The functionality of Motion, this forthcoming magic, LiveView, etc is all a step higher up. Motion uses ActionCable as the implementation mechanism, the "pipe" that data transfers over. But ActionCable itself is basically just "you can use websockets with Rails!" and not much else.
Well sure, and inevitably there are going to be gem(s) or framework additions that make it easier to send HTML down the pipe, which is how I read your comment. We don't disagree!