What about BSD?
"The Docker tech may even one day be OS-agnostic – Microsoft is a Docker partner and . . . has announced that a future version of Windows Server will support running containerized applications based on the Docker protocols – while Rocket is likely to remain Linux-only."
What about the various BSDs? Or the remaining commercial Unixes? (Count Mac OS X in either category.) Might Rocket eventually be able to work with any of them?
(I understand that even Docker does not presently support any of the BSD variants, nor any other species of Unix, and that FreeBSD and Solaris already have their own counterparts to Docker (Jails and Zones, respectively). (I believe that AIX and HP-UX do as well.)
And of course that CoreOS is, after all, a Linux variant.)