Recent statistics from the Association of American Publishers show that overall book sales rose nearly 5% in 2014. Of course, e-book sales edged out print books. And--no surprise--sales of children's and young adult books were strong, while sales of adult books were not.
As shown above, e-book sales vary by genre and by time of the year. Print books sell best in the 4th quarter for holiday gift-giving. E-books sell better in the first half of the year, apparently because consumers who receive digital devices as holiday gifts (tablets, e-book readers, etc) stock up on books. Nielsen has a detailed analysis of print vs e-books in its slide show here. Amazon lists the best-selling e-books of 2014 here.
So while book sales are far from dead, what's in transition is how people are reading. And how consumers are buying books. Barnes & Noble says earnings for its book division are flat, which actually is good news--considering how many book retailers have gone under in recent years. There is a future for US book sales, the question is what the marketing channels will look like and how the media will be consumed.