My kids both have iPads now (and this post is not about how they're growing up "digital natives"—it's much more practical than that). Theirs are a few generations old, hand-me-downs from an aunt and a friend of ours. We have other friends who are already eager to get the latest models and pass on their old ones (and, to be honest, we're looking forward to getting these as hand-me-downs from them: thrice-outdated tablets).
All of which adds up to the increasing ubiquity of 7- and 10-inch screens in our lives. As a family of two adults, one reading child, and one pre-reading child, we now have two 10" tablets, one 7" tablet, and three e-ink readers. (I note here that of those, we've purchased only two of the e-readers—avid consumers will have even more.) And this erodes one of the biggest competitive advantages of paper books over e-books in an academic context: the computing power of a big desk.
When I was in graduate school, it was not uncommon for me to be working with a monograph or two open on my desk, a Greek text of Josephus or Philo, a translation of the same, a Septuagint, a Hebrew Bible, a commentary or two, a lexicon or two—and a computer on which I was taking notes or writing. Obviously, the first of these to go electronic were the lexica (flipping alphabetical pages is a nearly-unmitigated waste of time). Then—mostly when reading secondary literature—the ancient texts. Again, flipping for references, and checking text against text (Josephus's telling of a story, the Septuagint's rendering, and the Hebrew) are sped up by clickable text. But for delving deep into the texts themselves, the 15" screen of a laptop was too crowded.
It's well-known that bigger monitors increase productivity. Academics, however, already had bigger "monitors"—to wit, desktops, with two, or six, or ten books and journals and notepads and scraps of paper on them. You could (I did) physically print out a paper and cut it into sections, and rearrange those sections in order to see if the argument made more sense a different way, or if a section of the thing you were writing was weak on evidence.
The sheer number of screens in our daily lives, increasing by the year, makes ebooks vastly more practical for the way academics work, comparing and weighing sources (whether textual, visual, or artefactual). The next step, by the bye, will be apps to make multiple devices work together seemlessly.