While I tend to agree that Red Hat is not likely to become the “Microsoft of Linux”, I do believe that server side Linux has a bigger hold than some folks might like to admit.

PHOENIX—Microsoft Windows will not suffer irreparable damage on the server side at the hands of the Linux operating system over the next five years, Gartner analyst George Weiss told attendees at the Gartner Open Source Summit here September 28.

In fact, in terms of worldwide server operating system revenue, Linux would come in below both Windows and Unix by 2011 in spite of its enormous growth, he told attendees in a session entitled “Enterprise Linux: Has it Arrived?”
While Linux would account for some $12 billion in worldwide server operating system revenue in five years time, significantly up from the $8.3 billion predicted for 2006, Unix worldwide server operating system revenue was expected to come in at $15.9 billion by 2011, with Windows revenue leading the pack at $22.5 billion, Weiss said…. Source: eWeek