Oh Duh!

"Microsoft went to a lot of effort to convince us to move from the one-time software purchase upgrade model to Software Assurance," said an administrator for a volume licensee who requested anonymity.  "We expected at least one client upgrade during this time.  Now, it appears our agreement may expire before Longhorn even ships, and no interim release will make up for that.  I want to get what I paid for; otherwise, this will have turned out to be an expensive move with little benefit."

eWeek.com

Well of course they did; duh.  How did you think M$ was going to keep up that revenue stream that makes Bill the richest man on the planet?  If you couldn’t see that coming when they announced Sofware Assurance I feel sorry for you.