I think this subset of people you refer to doesn't actually exist in the real world. I doubt the people who are saying "I'll support it when IE10 does" are ref

I think this subset of people you refer to doesn't actually exist in the real world. I doubt the people who are saying "I'll support it when IE10 does" are referring to not closing their img tags. They're referring to all the actually interesting features of HTML5, the ones that actually have a potential of changing the web: canvas, video tag, etc etc. Incidentally, all the features that IE probably won't support for a very long time. As stated before, most of these semantic changes were incorporated specifically because they already work, so chances are people are already using them. I doubt there's someone who is simultaneously adamant about using XHTML 1.0 style markup AND a big fan of IE backwards compatibility. The truth of the matter is that the part of the spec outlined in this article reads more like a best practices sheet for "practical" HTML4 than a spec for HTML5. By that I mean, most of it already works, and it is not likely to significantly change the web.