The global publishing industry should generate close to $358 billion by 2020. The bulk of the revenue should derive from the digitization of consumer books. E-book technologies will increase the awareness of titles and stimulate book sales, while e-readers, tablets and apps will boost digital sales in Japan, the US, and United Kingdom.
The bulk of physical book sales are occurring online. In 2015, the revenue generated by the global e-commerce market was $1.8 trillion, which is likely to increase to $4.6 trillion in 2020.
Last year 55% of people who purchased print purchased them from companies such eBay, Amazon, Walmart, and Alibaba. The primary reason why people are turning to companies like this are easy payment options, prompt delivery, and hassle-free return policy, which also increases the credibility of the e-commerce vendors.
e-Book sales for the past few years have been on the decline, but they continue to bring in billions of dollars per year for major publishers. Indie authors are also generating significant revenue, but many do not have ISBN numbers so it is difficult to estimate just how much they are making.
I think e-book sales will eventually rebound once publishers are able to adjust the prices. Right now they are too high and this has driven off casual readers.