I don't think Flash will ever go away - there's over a decade's worth of existing content on the web using Flash, such as from all those Flash game arcades all the way through 2000-2010, and some websites still use it. But I think it will definitely encourage adoption of HTML5. Firefox just (temporarily I think) disabled Flash due to the latest security vulnerabilities. I'm glad we don't have a Flash engine, otherwise I can imagine our forums flooded with upset users!
Shumway is an interesting project - it's an SWF player implemented in HTML5... that could allow browsers to drop the Flash player but keep support for running SWFs!