You can't extrapolate a few data points from today's trends to predict the future. You could just as well predict that since computer games has gotten insanely popular over the last decade, that's what one should focus on. This would be clearly incompatible with your future in the web browser.
If we are to learn from previous attempts to predict the future, some applications will probably follow this trend but in a few years the increase in computer power would cause large shifts in what people want to do. For a hypothetical example, by the time web browsers are powerful enough for office applications the fact that movies can easily be edited on that very same hardware made the desktop more important, not less.
It is worth noting that Wired magazine had a cover story a few months back on how web apps were "out" now that everyone uses native "apps" instead. Some people make it their living spouting these predictions. There's no need to pay them any more attention that necessary. Focus on what's important.