It's better to compare RedHat's Atomic Host with CoreOS Linux. Both projects are focused on providing a slimmed down Linux OS focused on running containers in a server environment.
Tectonic would be closer to RedHat's Openshift project/product, but that's not quite right either since Tectonic is not a full blown PaaS solution.
Nobody with widely-recognised components is going to just stop moving up the value chain to selling turnkey systems. That's where the serious bucks are waiting.
I expect that before too long, my employers' sales team will be seeing CoreOS and Docker sales folk as well as the existing competition from Apprenda, Salesforce/Heroku, IBM and Red Hat.
Tectonic would be closer to RedHat's Openshift project/product, but that's not quite right either since Tectonic is not a full blown PaaS solution.