Red Hat Enterprise Linux CoreOS (RHCOS) is Red Hat’s flagship container-optimized operating system. It is based on Fedora CoreOS, with each release subject to additional hardening/testing, and integration with OpenShift.
Migration from CoreOS Container Linux
Direct migration from CoreOS Container Linux is neither documented nor supported.
Production Readiness and Support
Red Hat stands behind RHCOS as a fully-hardened stable operating system, and support is included with OpenShift subscriptions.
If you just want to use the operating system, however, without paying for a full OpenShift license (for example, because you want to use another container orchestrator), there is no option available today from Red Hat.