I don't think he's laying out the whole flash vs HTML5 argument in that post. He says:<p><i>If HTML could reliably do everything Flash does that would certainly save us a lot of effort, but that does not appear to be coming to pass.</i><p>which is probably referring to how HTML5 does not have: efficient vector-based animation, support for audio mixing, strong tool support and ecosystem for creating interactive content, a pathway to run C code (Alchemy), etc.