Above is a chart which shows operating systems over different platforms. You can see that Apple's iOS is for phones and tablets however Microsoft's Windows 8 is for Tablets and computers. At the moment what Apple is doing is working (and that is why they are leading tech company) so I think it is too late for Windows 8. Maybe if they launched it 2 years ago it may have have had a chance, but unfortunately they didn't.
Windows 8 Tablet list and info: Windows 8 Devices