I don't feel like I can depend on any of these things, so I stick with the absolute bare minimum of what will build me a container. Which of these technologies will stay? Which will go? What will change as time passes? What will be deprecated?
In all honesty with Kubernetes talking about supporting Rocket and probably any other container technology that creeps up in the next few years, I'm leaning towards using that as the point of stability which I can deploy anywhere and know that I get the exact same API. Google, the leader in cluster management writing open source orchestration technology, think that's where I'll keep my focus.