HTML5 is a moving target that's changing everyday. Until the spec is 100% completed, finalized, and sealed, there's never going to be interoperability.
And interoperability is only one goal of HTML5. The other goal, in my opinion, is shiny features like Canvas, CSS Animation, and 3D Transforms. And Apple is doing quite well at those.
We get it. HTML5 was an inaccurate label to apply to the techniques Apple used in the showcase. But what's your point? What is Apple demonstrating here that isn't a valid example of how HTML is going to displace Flash? HTML5 is going to do video as well as Flash. HTML5 is going to do type and layout better than Flash.
And interoperability is only one goal of HTML5. The other goal, in my opinion, is shiny features like Canvas, CSS Animation, and 3D Transforms. And Apple is doing quite well at those.