Microsoft is going to rename all Nokia products to one name "Windows". They are rumored to kill off the Nokia family and drop the "Phone" in Windows Phone. This will confuse costumers on the difference between the Mobile and PC Os if Microsoft were to name everything under one name "Windows". Thus, there might be no "Windows 9".

http://www.wpcentral.com/microsoft-reportedly-dropping-phone-from-name#comments

http://www.winbeta.org/news/microsoft-reportedly-dropping-windows-phone-and-nokia-brand-names-favor-windows-and-lumia