In what time frame?
HTML5 isn't out yet and when it is, there are some huge gaps between what is possible on the web vs. locally. The bandwidth isn't quite there either. Take any hardware interface for example. Are we exposing all of our hardware to the cloud? There are many things that don't make sense on the web. I think all of the technologists are jumping the gun by a decade on this one. The only people that are moving to 100% web-apps are the most simple of consumers. Don't get me wrong the average joe represents a huge market share but they too will find the need for more capable local apps when they want to create or when they go to work.