I agree with you about the last thing somewhat, but not entirely. While RedHat benefits from people switching from CentOS to RHEL, it's not illegal to run CentOS, and the other direction is also available.

My company is currently using RedHat in a very large number (let say, we pay a lot to them...), but looks like we might end up switching to CentOS. Basically the price vs. amount of support we get from them does not seem to be worth it. And it is very close to what we would get from an Open Source community or by using Google.

But I do agree with the rest what you said.