Re: NO, Windows 9 is make-or-break
Make or Break will be when Microsoft announce an EOL date for Windows 7. As long as businesses can "downgrade" to 7, they'll just ignore Windows 8 while suffering the (just about manageable) pain of migrating from Windows XP to Windows 7. If MS has any sense left it'll announce that Windows 7 has guaranteed support until at least 2020.
If there's no user-compatible upgrade path from Windows 7 when it's EOL announcement arrives, that will be the date that businesses divorce Microsoft. (I mean divorce. Messy, acrimonious, and horribly expensive).
PS the desktop isn't dead, and never will be. It may run a non-MS O/S, or become a thin client for a noisy fat monster in the server room, but it will have a proper keyboard and mouse and a big monitor at the far side of a desk. What you need for real work, as opposed to playing, posing or skiving.