There will be an upstream community version of CoreOS, as Fedora is to Red Hat Enterprise Linux (RHEL), but that's still a work in progress. The Project Atomic site will eventually be phased away, but it won't be a dramatic move. The code itself will live on in Red Hat's container code repos.
https://www.zdnet.com/article/heres-what-happens-to-coreos-now-that-red-hat-owns-it/