Apparently Adobe is getting more and more comfortable with being a fallback for modern standards in out-of-date browsers. After adding VP8 to the list of supported codecs, they are apparently now working on 3D support. While we can be reasonably certain that Adobe wants to sell their approach to 3D as “unique” and will offer a proprietary 3D scene DOM to prove it, I would be very surprised if they blocked low-level access to that DOM entirely, since that would make WebGL more powerful and that’s a headline they definitely don’t want to see.
And where there’s low level-access there’s always a way to use it to emulate another API. So maybe in a not too far-away future we’ll see WebGL, SVG, WOFF, Canvas emulated via Flash in legacy browsers, so we can stop focusing on fallbacks and just let the dominant plugin (Flash) deal with the dominant legacy platform (InternetExplorer) while we are finally free to focus on content.