Hmmm - would there ever really be such a thing? I really don't think so, but since paper is supposedly made from trees, there may need to be something else. Last week, we all kinda agreed that the internet, while rather cool, isn't reliably permanent enough to preserve all our written knowledge. Though it may make it all easily accessible, unless you don't happen to have a computer.
So, with the treat of not being able to make paper any more, what else is there? We could go the Star Trek route and put everything in crystals or on chips the size of a credit card, but I'm thinking the concept of a real book would remain popular for a very long time.
Parchment was made from specially treated animal skins. Anyone want a book made out of parchment? We butcher plenty of cows, sheep and pigs for food, but would that be enough parchment for all the books generated these days? No, I'm thinking we'll need to go back to some woodish type material, just not trees. Trees will become a protected species one day, as more and more asphalt and concrete covers the world.
Maybe someone will figure out a way to utilize the leaves when they fall. Or maybe they'll be plastic, or not. Plastic is a petroleum product, and everyone says we are running out of oil. What about fiber? Something like cotton or silk might make good paper, and that's a renewable crop.
Oh, and can you imagine what would happen to the price of books made from real paper? What would be the value of a collection of books like you see in some movies sometimes, where some scene is taking place in a den and the walls are covered with books.
Oh gee, and that would start a whole new kind of theft wave. Stealing books. You'd have to insure them like rich people do with their pricey jewelry. Maybe you'd have to keep them behind locked and barred doors. How would you protect your precious books if it came to that? What kind of book would you settle for? What other ways are there for making paper?