To answer your question, our priority is to make sure docker works great on every distro, large or small, old or new. As some of the answers below will show you, sysadmin-world is quite a fragmented place, and I don't think we should expect "one distro to rule them all" situation. Instead I expect we will see more and more niche players solving a specific set of problems for a specific group of sysadmins, catering to certain tools preferences (openstack, mesos, hadoop/yarn, cloud foundry, juju, systemd, and so on). I think CoreOS is showing the way for a lot of those future distros. We want to make sure docker can be a good citizen in all of them.