Even if you sort of scale up the panoramas and such, all the assets like icons and such would be super low res. It would never work. I could imagine that in future you could write an app that runs both on Windows Phone and Windows 8 (provide high-res assets and they'll get scaled down when compiled for the phone or something), but existing apps? No way.
The main problem is that most assets intended for a phone would look too huge when viewed on a desktop, even when viewed without scaling. A finger-friendly graphical button for a phone is typically like 80 x 80 pixels. A standard toolbar button in a Windows desktop application is only 22 x 22 pixels. If you run an application on smaller notebook or tablet, a button that's as small as 50 x 50 pixels might be optimal for finger-friendliness.
IMO, the resolution of the assets, per se, is not the problem. It's the size of the controls relative to the screen size that's the problem.