The desktop already is and will continue to be a place for 'apps'. Most people install lotsa apps on their computers, just not from 'app stores' like they do their mobile devices. That's gonna change and soon.

Maybe one day everything will be 'the web' ala Google's Chrome OS vision. But that's a very long way off and will have to jump some high hurdles such as legacy software (particularly business) security concerns, speed, bandwith, data caps, etc. etc. etcm