There are millions of conventional PCs (desktops and laptops) running various Windows OSs in service. In addition Win 7 will be in support to, what, 2020 or something like that. In addition I believe there are many, many people that when they upgrade H/W will continue with conventional H/W. Perhaps moving from desktops to laptops, but still conventional.
IMO, there will be the desktop for the foreseeable future.