I've been keeping my eyes on this for years now.
It's been more prevalent in *non-fiction*, where Wikipedia is the poster example. In about 3 hours today I finally understood the Car Lingo of My Cousin Vinnie. (What is Four Degrees Before Top Dead Center?)
In Fiction, yes, the authors have slacked off a bit. Done right it becomes Dragon's Lair or Choose Your Own Adventure. We're still locked into the classical style from inertia by the big media companies that don't want to do any work to package 6 endings into a book.
Meanwhile, also nonfiction, talk about timing - after months of a fairly lame sig here, I finally switched it to actually announce my (Alpha 0.1 level) site:
One day I'd write a story like that with footnotes - you could breeze through the story or you could wander down the Chapter Notes to look at Moore's Law, Aleksandr Solzhenitsyn 'University of the North Window' (they had so many University Political Prisoners that they got fed up and taught classes in the Gulag Prisons!).
And more. I very distinctly remember a footnote by Mr. S. that said "If I ever have time I want to write a story about ...". He might be out of time, I might have time to weakly honor his request with my feeble story skills.
Point is, the Academics might be as much as ten years ahead of the curve. The existing companies want to make money on existing products, so they mold the landscape. But I am a champion of the HyperText Writing Method, which I call Writing Like Software. Sure, laugh if you want at my "0.1 Alpha" version, but at some point, enough content will get to all the nodes that "You" (General User Base) will stop laughing and y'all will go "Oh. Right. I see now."
That's the future of writing. Elsewhere I have ranted about Print Live On Demand, the Future of Books. So sure, when an Author submits and update, the next copy of the book that gets Live Printed contains the new material.