I've not seen anybody else suggest it, but I reckon even before Windows 8 was released there was a marketing report in a desk somewhere with a couple of empty boxes to plug in numbers from windows 8.
What does it say?
Well it says that the data compiled show that home users almost never installed an application from disc, entirely using the windows store to buy their software. So in future in order to provide our users with what they want and to improve security with Windows 9(tm) Home and Home Premium editions will only run software from the Windows Store. Users wishing to install specialist niche software from disc are recommended to buy the Windows Professional version of the software.
In unrelated news, the price of Windows Professional has risen by 100% for single licenses.