Though there's that, too.
But if the publishers (and established authors) can convince their market that this is the New Bestest Thing Evar, then all novels have to be published this way or they're too "crude and amateurish." And that means that the self-publishing authors, who have zero barrier to entry in to the market, can no longer afford to self publish, because who can afford all the multi-media crap that adds nothing to the value of the novel?
This isn't a new idea. Publishers have been desperately trying to find a way to keep people from eliminating the middle man since Kindle made it big. Multi-media crap is the most obvious way, since it's too much work for one person to do alone, and too expensive for the self publisher to buy done. Unfortunately, for publishers, it adss nothing to the novel reader, and this scheme/scam will fail just like the multi-media schemes/scams before it.
People who want multi-media will buy DVDs of movies, not web pages that pretend to be novels.
It's a pity that publishers aren't willing to try the one value added service that will actually appeal to readers: actual, you know, editing and shit, like they used to do, so that their product doesn't suck donkey balls.