Kubernetes could move to rkt or even the now standard systemd stuff, end users would hardly know the difference. The container format isn't a very strong lock-in effect and most people are probably better served without the image type format anyway (as the Linux block layer wasn't really constructed with that use case in mind, and fixing the plumbing will take longer time than developing the orchestration tools which is what'll win the users).
Docker the company have few options to monetize on Docker the software when it becomes commoditized. They seeminly chose the Enterprise way, which consists of pretty orchestration tools and integrations with Active Directory. (A perfectly valid option, which worked out well for VMware.) That's a dead end now that Kubernetes won container orchestration. It will be interesting to see where they will go next.
