Once Steam comes to Linux, I don't see many reasons why a lot of gamers won't switch over. Many of the people I who use Windows to develop in Python/Ruby/etc use either a VM or SSH into a Linux box, simply because they want to game. I think many people will not want to pay the Microsoft tax, especially for Windows 8.
Does the Gnome foundation think they'll acquire users because they're resembling the user interface of tablet? They won't they'll continue to lose users who are annoyed with trying to use a tablet interface where a desktop environment should be. I'm so sick of the horrible design innovation coming to the Linux Desktop. Fact of the matter is, the Linux Desktop is still for power users, becoming more and more different without innovation will only aggravate those power users and they'll switch to other alternatives. When KDE4 came out, many switched to Gnome 2, and now those users are switching to XFCE or looking for other nice alternatives, such as tiling window managers.