CoreOS is SystemD already
CoreOS is basically a Gentoo Derivative but with the package manager(emerge) removed.
SystemD preinstalled + Docker.
And "ignition" - some JSON configuration file which fills out SystemD unit files - so there is no escape, no C compiler, and everything runs in a container - or is statically linked, or is just a pain to install.
They go to some lengths to disguise the Gentoo heritage, but it's getting some traction with DC/OS (separate software bundle from Mesophere) being the quick start tooling for Kubernetes/Mesos clusters on AWS, and DC/OS choosing to make that bundle use CoreOS as a base rather than say CentOS or Debian.