@AC -- Fedora Revenue

The issue here is not charging money for Fedora, but converting people from Fedora into fee-paying RHEL users. How much are they prepared to pay for support and stability? Is $750 per annum too steep? Is $5 in perpetuity less than it costs to provide the service? Converting CentOS users to RHEL is harder -- they already have stability so you're left with providing support (which they don't need) and access to patches quicker (which they mostly don't need).

There's no way I'd pay for Fedora either, but I might be prepared to spend a small amount to get RHEL and its updates and I'll skip the support thank you.

Of course, where Red Hat can and do differentiate themselves from the free hoi polloi is in support, especially when it comes to complex things like HA clusters, but that's not where the mass-market money is. And that's the challenge.