I think that since adopting the 2D desktop metaphor, we've all started working with way too much data for it to be reasonably represented as a 3D world. The trend in OS design recently seems to be away from representing physical objects and more towards

  * dashboards (Windows 8 start screen and Mac OS dashboard) 
  * lists (browser tabs, Windows taskbar jump lists)
  * search

I think we're evolving towards a common visual language for representing information, and the concept of a physical piece of paper or a table on which to store it is going to become a distant memory.