That would be easy the hard part is solving the responsive image problem. How can we know what quality image to send to a device?
The problems are shifting from display/device types to network types. Great you've got a 1080p phone but we can't shove down our retina quality images on 3g. Nor would you want use to use your battery life for that.
http://en.wikipedia.org/wiki/10-foot_user_interface
Imagine a responsive web design that goes from 10-foot all the way down to mobile; now that would be impressive!