As per the question in the FAQ about open sourcing CoreOS's technology, we can assume it's going to become open source, at least:

https://www.redhat.com/en/blog/faq-red-hat-acquire-coreos

It will probably continue to be available in some paid commercial offering with well defined releases and lifecycles, as well as a community-supported free-in-both-senses offering which moves faster. Red Hat repeatedly uses this model across their portfolio.

Can't answer the OpenShift question - I have no inside info from either company. But open sourcing it is the bigger impact.