You know, eventually the line between the desktop and the web is simply going to disappear. Web apps will cache more data on the user's hard-drive and run more code on the user's CPU. Meanwhile, desktop apps will store/backup more data online and offload more computation to servers (or maybe other desktops). There's huge potential for libraries or tools that make developing half-desktop / half-web apps easier.

Question is what form will those tools take. I wouldn't be too surprised if the OS just became a ginormous browser that could talk directly to hardware like the graphics card and a huge cache for storing "installed" web apps.