The great thing about Flash is that it allows for non-professional programmers to make great stuff.
The same way iPhoto allows for non-pro photographers to make nice photos.
The same way that iMovie allows for consumers to make decent movies.
Sure, Photoshop and Final Cut Pro allow for way better photos and videos. But the average consumer can't do anything with that.
If you're a pro and you know how to do HTML5 effectively, then fine, do it. But many people don't know how to program because they are not programmers, simple as that. They can still make something quite complex by themselves with Flash.
Thanks to Flash, I can create my own website, which allows me to update it whenever I want, without paying a developer who takes arbitrary decisions. I'm a photographer, and I don't have the energy or time to learn to program a proper website. When I'll be rich and famous, I'll employ a web developer.
Until then, I hope that Flash will stay what it is today and that I can easily keep making my own website.