I've thought for a while that certain web technologies that Google is developing or promoting (e.g. WebGL, NaCl/PNaCl, V8, Chrome app store, Chromebook, etc.) has implied a vision of web apps being just as capable as desktop apps, perhaps even in categories such as video games that need raw access to the CPU/GPU. However, progress towards this vision seems to be going much more slowly than I would have expected, and desktop apps will no doubt continue to fill certain needs and niches even if a fully realized web platform is achieved.

Of course, mobile apps (and the consumer electronics revolution that has allowed many people to consider their phone as a primary computing device) are also competing in this space.