Earlier quoted context omitted.
I don't understand why the Flash runtime is needed or why it matters that it went through a "demise". I was under the impression that you could just export Flash to HTML5 and javascript now? I'm not a flash developer so you'll have to forgive me if this is a dumb question.
(1) The rumors about HTML5 are not exactly true. (2) There are good open-source Flash runtimes. (3) The selling points of Flash were the no-installation experience and really good development tools. Both aspects are somehow lacking today, so the momentum is gone. Maybe someone will produce a great and accessible tool to create comparable HTML5 experiences, and that thing will become popular. But not yet.
Or is the issue that the export-to-HTML5 functionality in those tools is just not fully done yet?