Today Microsoft announced Windows 10. Evidently, there will be no version 9.

http://www.marketwatch.com/story/microsoft-offers-first-peek-of-windows-10-2014-09-30-15103594

http://www.computerworld.com/article/2689409/microsoft-unveils-spiritual-successor-to-windows-7-by-going-to-10.html

Microsoft executives said Windows 10 would launch sometime after next spring, but they declined to discuss other details, including timing or prices.