Even at the high end, however, as Microsoft moves its customers to a service model through Azure, it becomes less important to monetize the Windows software directly, Gillen noted.
"Microsoft's revenue increasingly comes from the compute services rather than licensing software, and by selling a wide collection of related services such as Office 365, OneDrive, Bing, etc.," he said. "So would it make sense to open-source Windows in, maybe, 10 years? Quite possibly."
Sign up for CIO Asia eNewsletters.