If you haven’t already, check out HTML: The Markup Langauge. Besides being a cool new recursive acronym for HTML, it is a reasonably-sane document. Also worth a look: Differences between HTML4 and HTML5. Many of the ideas from XHTML 2 (of which I was an editor at one point) are there.
I think it’s time for the W3C to show some tough love and force the two (X)HTML Working Groups together.
A while ago, I argued that the existence of both Flickr and Yahoo! Photos as an effective two-pronged strategy. Look how that worked out–Y! Photos is permanently shuttered. While there were benefits including a broader potential reach, in aggregate the benefits didn’t amount to more than the immense cost of having two parallel efforts. Same here. -m