That said, Flash still has features that are missing from HTML5.
1. One file distribution.
AFAICT HTML5 has no real ability to do this
2. Easy streaming
I suppose you can break a HTML5 app into multiple files but with flash there's one file and it can start running the content of that file when only some small percentage of it has downloaded. And, it just magically happens or rather it's super easy to setup. Reproducing that in HTML5 is a huge chore.
3. Not running when not visible
HTML5 has no way to stop an animation when offscreen. If you have a requestAnimationFrame Canvas or WebGL or element based animation and your element is scrolled off the screen HTML5 will still execute your code. Flash will not. So, blogs aggregating flash content work. Blogs aggregating canvas/webgl content don't even exist or unlike flash each item needs to be on its own page. There are some workaround but they require you to modify all content where as Flash you can use 3rd party content and still get this.
4. Can copy to clipboard
Yes I know that's considered "unsafe" and yet nearly every website that needs that feature uses flash for it. Google Docs and GMail both use it even though Google's Chrome team claims they won't put the feature in HTML5 because it's unsafe. They need to make up their minds.
I'm sure people who are more familiar with flash can name more features they wish would make it to HTML5.
And on top of that I can easily block flash. I can't block HTML5 so much :P