It looks like the anticipated 2015 Windows 8 update, code-named 'Threshold' , is actually going to be released as a whole new iteration of the operating system. By calling it Windows 9 it looks like Microsoft are hoping to draw a line under Win8 like they did with Vista.
We will still be getting an update to Windows 8.1 this year sometime around April. According to ZDNet the update will be free and there are some indications that they are looking for ways to “make Windows 8.1 friendlier for mouse and keyboard users.”
They'll also be introducing Metro 2.0 or Modern UI 2.0, or whatever else they decide to call it, which will allow Win8 apps to be run in windows on the desktop should you so desire.
What will 'Threshold' / Windows 9 offer? Well, judging by the change of name to become a new iteration of Microsoft's PC operating system we can expect they'll want us to pay for it. If it's big a revolution as some of the rumours and postulation hints at then it could well be worth the upgrade. Microsoft have hinted that they're looking to consolidate their operating systems across PC, phone and possibly even console to create a 'One Microsoft' ideal and Windows 9 could push us ever closer to that. With PCs and the Xbox One sharing both the same hardware and the same software kernels that might not be such a crazy rumour.