At the end of last week Ian Hickson who edits the WHATWG and W3C specifications for HTML 5 made this illuminating comment:
If anybody is following the, sometimes uncomfortable, discussions on the new specification, this helps put it into perspective.The WHATWG doesn't actually work on HTML5, it works on an unversioned specification for HTML that is to be continually maintained. "HTML.next", if you will...
The WHATWG is looking to the future including beyond HTML5, which may or may not be ready to become a fairly firm specification.
He goes on to say that the HTML 5 has been retained at WHATWG because some people wanted it so. (Marketing reasons.)