Neowin picked up a story that quotes Microsoft Chief Evangelist Steven Guggenheimer saying that he's uncertain about the future of the desktop UI. First he says that over time, it's likely to go away, but then he adds that he's not sure if it will ever go away completely:
A TechCrunch article quotes Microsoft Chief Evangelist Steven Guggenheimer saying, at least at first, "Over time, it’s likely to go away." However, the article mentions that Guggenheimer quickly changed that statement, saying he was not sure if the desktop UI will "ever go away completely."
Certainly applications such as Excel spreadsheets or advanced 3D modeling programs will still need to be controlled mostly by the mouse-keyboard combination on a desktop interface for a long time to come. Guggenheirmer states that at the moment there's "this weird balance between [the desktop] ending up being less critical over time, but it probably never goes away completely. Or if it does, it’s hard to predict when."