I think that just speaks to books in general, and is not necessarily indicative of a lack of interest. More people are seeking their entertainment online, or via e-books. I personally read a lot, though I haven't purchased a physical 'book' in 5 years. Libraries are seeing a reduction in customers, which I hope means that they're reading more e-books vice not reading at all.
Interestingly, Cross Cult (the German publisher) said on its Facebook page, that 25 % of their number of sales are ebooks. I don´t know about American publisher or other countries. It was a bit surprising, because many fans railed about ebooks via Facebook. I prefer the novels in the printed form.