I think non-DRM PDF will be around for a while to come. It's, once you get past the crappy Acrobat, a fairly nice format for things that are either originally or traditionally in print. Manuals, guides, similar especially. Not so much for books.
Also I think things like Xvid and OGG should hold up quite well, as they
are open-source, which means there's usually bound to be
someone still developing them. I can't really say about the other ebook formats, as what I use is, generally, HTML + Plucker.
But I really don't think DivX or MP3 will be around in much force in 10 years. There are much better audio codecs (such as the other two popular ones - OGG and M4A/AAC), and better-or-equal video codecs. DivX is better in it's class than MP3 is, however.
One thing is, once support for a codec is in a media player like MPlayer, VLC, or Xine, I doubt it'll be removed, ever, without a good reason (like it breaks something else), so hopefully those players will still be able to play old video files ten years from now.
Edit: Oh, and on HTML, etc... Those *can't* entirely die off.
Because they're just text with formatting markup. Even if we no longer have programs to interpret the markup, we can still take the raw text out of it.