People regularly convert verbs into nouns. It's a semantic error, but it makes the invisible process of "making the web better" visible to the muggles.
verbing nouns does indeed weird language, but that's not the point here.
The point that analysis of HTML5 as a standard is not the point of the current effort to improve the web, and improve computing in general.
It does not matter where HTML5 and Flash happen to stand at the moment in aggregate usage across companies. Who cares. There are many reasons for adoption of each technology, dependent on the circumstance of each company and their business models.
That's why HTML5 as a noun is a bad banner, avatar, symbol, whatever. Web2.0, nebulous as it may have been, could not be confused with an actual object.
HTML5 suffers the same problem that XML did. People thought anything that touched XML was going to be the wave of the future, and improve everyone's lives, and be both machine and human readable, and lead to a revolution in how metadata was transported.
It is true that XML lead to cool new capabilities on the web. It also was not a panacea, nor did it instantly make any project that used it awesome (XML config files are one of the most heinous digital inventions ever).
People should not confuse the movement to create better web technologies, with the web technologies themselves, or we will all miss the point.