Keith Boone, well known and liked Health IT standards geek has written up a proposal that would make the next release of HL7 CDA based on HTML5 rather than XHTML.
I have just become more deeply familiar with this set of standards as the result of the extensive research I have done on my new book on meaningful use of Health IT.
I can say, without a moment of hesitation, that this is a really good idea.
Everyone should support this proposal, b/c otherwise, CDA is a huge mess.
Which is not to say that an HTML5 version would not also be a huge mess. But I believe that it would be less of one.