There is another big reason why old technologies are hard to dump: cost.

VHS hung around for a long time because of the expense of replacing both equipment and media. When people started dumping VHS big time, video libraries suddenly became affordable to people who couldn't afford it before.

Books are facing the same problem, only a few hundred years worse. It is taking tremendous efforts and the vast finances of major corporations and universities to digitize existing libraries. Even once that's done, libraries and individuals have huge investments in books that can't be replaced inexpensively (because copyright). Oh, and print books are still orders of magnitude cheaper than ereaders. You can easily pick up 50 to 200 books for the price of a low end ereader. An ereader that will cost you even more money if you want to buy books, because books don't exactly grow on trees in the digital era.