The main point of the article as I read it is that HTML5 is made up of a variety of technologies, which have different levels of completeness and readiness for the general public. To say that HTML5 is not ready to be deployed therefore makes no sense.

HTML5 is just a buzz word to describe recent advances in web technology which should be used in the same manner as us web developers have used web technologies for many years: consider the target audience and provide adequate fallback mechanisms if necessary.