I think we're seeing a shift in focus in the container world from container runtimes such as Docker, to container orchestration systems such as Kubernetes. At some point the container runtime becomes just an implementation detail.
Unless Docker finds a way of moving up the stack they are going to have a hard time defending their current valuation. Their current efforts provides close to zero monetizable value.
Orchestration isn't monetizable either. Amazon is giving it away for free on ECS.
Fleet, Mesos, swarm and kubernetes are effectively different implementation details too.
Operating these things as infrastructure services with high SLAs is a money making business.
I hope there are other ways to make this stuff a good business because CoreOS, Docker, Hashicorp, and Mesosphere et al are doing pretty darn excellent engineering.
Unless Docker finds a way of moving up the stack they are going to have a hard time defending their current valuation. Their current efforts provides close to zero monetizable value.