There are literally millions of experiences out there that can't be done with HTML5, CSS and JavaScript. if you want proof, go to theFWA.com and have a look around.
For every bad flash solution out there, there are some quite fantastic ones.
Flash gives you control of the experience in ways that by any metrics outcompete HTML5.
This might not mean something for most people here at HN, but for quite a lot of people (the same ones that Jobs is catering for with his iPad) it's given them many great experiences. Experiences that are not going to be matched even by the best HTML5 developers out there for quite some time to come.