I really don't think Microsoft can generate enough developer interest to even bother. I've been asking that question for a while now. Since everything is pretty much gone mobile, I think this will be the last place to find any real useful app. Microsoft should sincerely put forth an effort within its own company to come up with some. As it stands now, a pretty pathetic collection in my opinion.
The thing that's crazy is that Windows is still the most popular desktop operating system in the world, by a large margin. The fact that they don't seem to attract as many talented independent developers that make polished software for other platforms is really surprising.
I think the problem is that there aren't enough copies of Windows 8 to entice developers to develop for the "Metro" touch environment.
The desktop apps are still available via the web and that doesn't help Microsoft to sell Windows 8 to people who are skeptical of the operating system.