While the number of books available grows every day, there is no evidence that demand for books is increasing at a similar pace, let alone in a way that would support the writing careers of the multitude of authors, or even a majority of them, even if e-books and indie publishing increase the share of sales that individual authors receive.
–Dana Beth Weinberg cuts the pie.
Hence, I think, some of the sudden push towards subscription services, ebooks, and downward spiralling prices: in a content oversupply, the point is to get as many consumers buying (or borrowing, whatever) much, much more content than they could ever possibly actually read. If someone reads 11% of your book on Kindle Unlimited and then abandons it… so what? You still get the sale, right? And it’s not like it is in the paperback market where that individual can foist their unread books into the second-hand book market, representing a (potential) lost sale for the publisher. (See also: resistance to nascent secondhand ebook markets.)
In other words: it’s the App Store all over again. And look where indie developers currently are with that one…