<shrug> Beats me </shrug>
The HTML5 working group is chartered to work through December 2010 but that could be extended to 2011 or 2012.
There's a big difference between 1) specs being complete, 2) browsers supporting them 3) those browsers being in widespread use.
Several years normally.
HTML5 complete - up to 10 years away. although parts of it are being implemented by browsers as we speak
CSS3 complete: similar. Browsers are falling over themselves to support elements of it as various parts of the spec move through their approval stages.
It will take years until HTML 5 will be fully supported by all browsers. The newer browsers like Chrome from Google support it and IE9 will be ready for HTML 5 too, but we all know IE has always technical problems, so...