Ask HN: Why Doesn't Red Hat Fold CentOS and Make RHEL Free?
This is close to what Red Hat already does - and seems it might align more potential users. If you're using free CentOS, and get into a jam - there's no-one to call for support, other than forums and your knowledge. But, if you had RHEL proper, and got into a jam - you could call Red Hat, and pay for a support package. They could even charge a high hourly premium for out-of-contract support calls, and offer to upgrade you into a support contract, etc.