I do think it's a fight to the death for container orchestrators. The configuration files required to run complex auto-scaling systems can add up (and require DEEP understanding of all the systems involved and how they interact with each other) - Most developers don't want to have to do it for more than one orchestrator; especially since there is no straightforward migration path from one orchestrator to another.

Also, learning different orchestrators is a lot of work. Sure, maybe Mesos does more than just schedule containers, but that doesn't matter because a standardized orchestration platform is the main thing developers need right now - For orchestration to become truly standardized, there needs to be a single big majority winner.

It reminds me of the Minix vs Linux debate in the early days of operating systems; Minix was modular (microkernel) while Linux was monolithic. The reason why Linux won is because it provided a single consistent standard platform on which to build and configure applications. I think the same is going to happen here and I think that Kubernetes or Swarm are better placed in that regard.