The browser is already a thick client with local storage and lots of local logic. The difference is that the entire client is shipped to the browser on demand.
Ok, that's an interesting point. I'd argue that local storage hasn't really taken hold yet, i.e. the large majority of sites and apps don't work offline, but yeah, it already stretches the notion of a thin client (hence my beef about using this term on where we're headed in the future).
