An Event Apart has been doing its thing in San Francisco, and one of the speakers was Jen Simmons. In HTML5 APIs Will Change the Web: And Your Designs, she said HTML was "more than paving the cowpaths. It's more than markup. There's a lot of stuff in the spec about databases and communication protocols and blahdiblah backend juju. Some of that stuff is pretty radical. And it will change how you design websites."
As outlined by Luke Wroblewski on his blog, the talk by Simmons argued existing HTML5 coverage tends to focus on new elements, despite there being a "whole additional set of technologies coming that web creators need to be aware of: HTML5 APIs and beyond". Simmons talked about how web designers have been working within the limitations of relatively basic web technology, and have almost stopped thinking about such constraints, but this is not where the web will be in the near future, owing to rapid evolution, in part driven by HTML5 APIs. The various examples clearly imagine a much more app-like environment, but driven by open standards, the beginnings of which we're already seeing online. Additionally, Simmons said people need to rethink how content is created, and finally break from design's past in order to fully take advantage of its future.