Seems to me the best way to address the mouse oriented interface of existing applications in a touch based environment is to use a stylus, which buttons that simulate mouse click on it, and some form of wireless technology that triangulate and determine the mouse cursor movement on screen when you move the stylus on top of the tablet surface even without touching it. This should be possible using today's technology, as evidenced by the S Pen in Samsung Galaxy Note 2.
The greatest strength of Windows is tremendous amount of existing applications. Microsoft should have really done more to create a stylus that can do this and pair it with the Surface, and sell it to support tablets built by other third party vendors. Instead, they ignore the need to improve the usability of existing applications in a touch-based environment, and bet all their hope on the new Metro UI interface and the future apps. That approach has thrown away significant advantage of Windows. They are currently trying to market Surface and Windows 8 as productivity machine in a touch based environment by bundling Office. However, notebooks are really much better as far as mobile productivity goes and tablet is really more suitable for entertainment and light work. How soon will people start to realize doing real work on tablet without a keyboard and mouse is a pain? Sure Surface RT does include keyboard and mousepad in the touch cover, but does people reall want to pay that much extra instead of getting a notebook with real keyboard and true backward compatibility with existing applications?