You should take a look on these samples:
You can also animate vector (svg is native i modern browsers, some gpu accelrated even) with fallback for older browsers, (which raphael takes care of) Maybe not there yet, but another sign that flash plugin will die.
About the open source project, sure, but no one have bothered making a good plugin then, why bother.
I think they should open it, and it should not be plugin, but a protocol, as in flash://adobe.com would launch the app/anim/advanced air application/whatever in flash.app / flash.exe or your open source choice for executing flash.
And at this time when you can do everything for the most in html (html5/csse3/js) it just need skills., why should you embed the really advanced stuff flash could do like 3d games etc. For HTML pages, html is the best.
Then I do not need to restart the browser everytime there is an update to flash either, much safer than a forced execution of flash (I use flashblocking), I do not see the reason for a page to have a lot of different flash animations one page, that scenario would usually be just ads.
And you do not need flash for playing video, that era is over. If you are a developer and can not manage to make a cross platform player / solution and a worst case fallback to flash, you should not develop that page.
Never test for an error condition you don't know how to handle. -- Steinbach