Less than two months after the launch of Windows 8, rumours have already started emerging about the next version of Windows. It's code name for the time being is 'Threshold' and rumours suggest it will launch in early 2015.
Apparently, 'Threshold' will add more features to Windows, Windows Phone and Xbox to unify the three platforms even more. It is also highly likely that Windows will soon just have one App Marketplace for Windows, Windows Phone and Xbox which will replace the current 3 app stores. This is similar to what Apple has, as they only have one app store for iPhone and iPad.
In my opinion, I think making one platform for all form factors of device will be very risky; it will probably either reestablish Microsoft in many markets or it will break Microsoft meaning they have wasted millions of dollars and over two years in research. I, personally wouldn't want my smartphone running the same operating system as my Xbox however I'm sure some people disagree.
Microsoft are putting all of their eggs in one basket and in an an operating system which hasn't even been proved that popular.
I saw this coming earlier this year: Microsoft One