We have a nice discussion going, but I think you missed both of my points.
"Once you have standardized page size and other challenges inherent with POD, you might as well just be downloading an e-book. Cost may be an issue for e-readers today, but you already can get some pretty damn cheap e-readers if you are willing to buy something other than the big name brands. So if you are talking about the future of books, not just trends over the next 5-10 years, it is most likely going to be incredibly cheap color e-ink tablets that most books are read from."
I think you mixed up the nouns of who is doing what.
A. Harvard Book Store (in discussion with the Rights Holders) has this same big databank of the digital files. But instead of a e-reader file, it's a POD machine file.
B. Me. *I* am not the one standardizing page files! And there are no challenges! Here, one min, lemme go to my shelf with the prototype books. I have here:
"The outlines of Mahayana Buddhism" 7x4.5 inches, 410 pages.
and "An Introduction to Mahayana Buddhism". 8.5 X 5.5 inches, 230 pages.
Each cost about $5. I get all that old time feel of having a physical reference, including turning down page corners and making pencil notes. And I just walked in, paid the cashier, and walked out with them an hour later. So no problems for me at all!
"They are for highly specialized content and for reference information that has not yet been posted online (which is more and more rare as the years go on)." All non-fiction content is highly specialized! A good non-fiction author too his/her time and created the info flow to demonstrate a larger premise. Not a single one of the 1000 ish books in my library can be duplicated *in the same order* online! Sure, with exhaustive work page by page you can begin to do it, but ... that's the point of a book!
The whole point of POD is ... on demand. You can bulk buy the 1000 books in digital format, then for the few you want in that old time format, you'd go down to your properly equipped store (theoretically *any* store!) and get your physical copy.
The tech has been here for half a decade. A little bit of sunk cost for the machine. But paper wise it might be as low as $2 a copy in raw costs. But the publishers are fighting it.