Ok, a couple more: If everybody that does their very best to do the stuff they do today in flash would seriously try their hand at JavaScript the need for flash would be relegated to very few sites. And it wouldn't hurt to have browsers support H.263/H.264 natively either.
If Javascript/HTML/CSS had the cross-browser support for scripting, display, formatting, etc that Flash/Flex does, I'm sure more people would consider it a serious option.
There are many things that can be done in Flex that are impossible or extremely hard and fiddly in Javascript (and I'm not talking about animations, but about user workflow tasks like uploading a bunch of files). There are many other things that can easily be done in HTML/CSS/JS but don't quite work across all major browsers. That last 1% really kills you by taking a huge chunk of time to fix.
Flex interfaces, on the other hand, work exactly the same no matter what browser you're using. Many of our clients are still stuck on IE6 because of corporate policies. Trying to reproduce our interface in Javascript would be very hard and wouldn't work properly for most of them.
To paraphrase you, if Javascript had more of the capabilities of Flash maybe Flash wouldn't be needed.
Ok, a couple more: If everybody that does their very best to do the stuff they do today in flash would seriously try their hand at JavaScript the need for flash would be relegated to very few sites. And it wouldn't hurt to have browsers support H.263/H.264 natively either.