Amazon Pacman Slide
The Real Reason
These are from an Author Earnings (Jan 2017) which explains things well. All of the slides can be found at
Author Earnings Slideshow
What Author Earnings believes happened is that print book sales rose because Amazon responded to Agency by discounting Print Book sales. This has now stopped.
The slides are good viewing. Amazon's ebook sales for 2016 were up 4%. I suspect that whilst many of us may well be buying less ebooks, the growth in the ebook market is more than sufficient to offset this effect. Another interesting point is that October 2016 finally saw an uptick in traditionally published ebooks. No reason for this is put forward, though I suspect that some traditionally published ebooks are being discounted and sold at more appealing prices. Sadly, though, my experience is that such publishers seem to still mostly want top price even for most of their back list. And according to AE, the big question now for publishers should not be digital v. print but online v. Brick and Mortar.
Anything relating to books in the Guardian and the New York Times should be viewed with suspicion. As Cinisajoy said above, this type of headline is clickbait, pure and simple. Or perhaps wishful thinking.