My favorite way to picture Kubernetes is to think of it as a distributed operating system. It generally happens to be run across Linux hosts and is used to run Linux containers, but the Linux parts are incidental, like the specific model of CPU in a desktop system. The Linux parts aren't core to Kubernetes' abstractions, and it's possible that Kubernetes could add support for hosts and container runtimes that aren't Linux but instead platforms more streamlined for Kubernetes usage without historical baggage.