After a few leaks and speculation surrounding a Windows 9 event set for September 30th, Microsoft has now made it official. The next steps for Windows and the Enterprise will be announced in San Francisco on September 30th according to invites now being sent out and it's highly expected a technical preview of the new OS code named Threshold will see release.
Microsoft has already stated that the next version of Windows will bring back a version of the Start menu for the desktop UI that went missing with the launch of Windows 8. It will also have the ability to run Modern apps in windows on the desktop. Rumors about Threshold claim that Microsoft may do away with the Charms bar in Windows 8, along with adding support for virtual desktops and the Cortana digital assistant that's currently being used for Windows Phone 8.1.
Source: The Verge