Miguel,
thanks for pimping
Swfdec. But I think your conclusions are wrong. Flash is
not even close to what I’d suggest as an option for “rich
media”.

For a start, the currently supported Video formats for Flash
are Sorensen Squeeze and On2 VP6. As far as I know, both of
those companies are actively fighting Free implementations
of the codec. That makes Flash video as bad or worse than
VC-1. You can play all 3 of them with FFmpeg btw.
Then there’s the fact that the interaction between Flash and
browsers is crap. You can execute Javascript from the Flash
file and you can execute predefined Flash functions from
Javascript, but there’s no DOM or anything. But what about
integrating Adblock, the “animate only once” option, popup
blocking or all the other things you want integrated?
As for the things you mentioned: The Flash spec is
semi-open, in the sense that you may not use it to write an
interpreter for Flash. That’s equivalent to closed for
everything you care about. And the spec covers the file
format only, not the video formats used or what script
objects are supported.
And you can populate Flash files using remote data. You can
even chose between XML and Flash. The XML needs to be
interpreted, but I’m pretty sure there’s convenience
libraries for you that do that.

And it’s not like the Free alternatives are far behind in
the game. HTML5
has a video tag and SVG is far superior to anything
Flash offers in drawing options. Especially because it’s
scriptable while Flash shapes are not.

There’s 2 things missing:

• Simple animation support: Flash makes creating
  animations extremely easy. Doing the same thing in
  anything Free (HTML, SVG, even Gtk) requires being a good
  code monkey. The example above required NO coding.

• Authoring tools for rich web applications. Depending on
  who you ask, the best Free authoring tool is either vim or
  emacs. There’s the Gimp and Inkscape of course, but neither
  does animations nor scripting, so it’s pretty useless for
  doing rich web apps.

So I can tell you what you want. You want to create an
awesome authoring tool that integrates HTML5 and SVG and
make Webkit and Mozilla handle those. And after that I bet
rich web apps are Free.