I've thought about it, and if you're trying to achieve a true upsize of everything 100% uniformly, then you might as well just downsize your resolution. It achieves the exact effect your asking about. In fact, it would be exactly like the Vista style scaling, except things won't be blurry. The only downside is you won't have apps that ignore the scaling to use the full resolution for things like HD video. But, if you have apps ignoring the scaling you've chosen, then it's defeating the purpose of the type of scaling you're asking about.
A possible solution in the future (for OS designers to add to their OSes) would be for users to choose a scaling that behaves like a smaller resolution, then allow apps to ask for your permission to use the full resolution for things like video. e.g. a video players launches an HD video, and windows asks if you'd like to allow the app to use unscaled resolution (with a note that this is good for things like HD video, etc).
A current solution is to allow apps to go full screen and change the video display resolution like games do, but most non-game apps don't implement it. For example, it'd be nice if I could put my desktop at a lower resolution for every day use so interface things and fonts would be bigger, but then an app like Chrome could go full screen and change the display resolution when playing a video. This would be the best solution if Windows (or any OS) made an API to allow apps to do this resolution switching easily when an app goes full screen.