This is old news in Japan, where long commutes on public transportation create a thriving demand for reading material.
The read-on-your-phone trend, while not exactly cutting edge in the U.S., is nonetheless relatively new here.
As the article states, phone reading apps, rather than dedicated e-reading devices, represent the wave of the future.
I haven’t used my Amazon Kindle (purchased in March 2011) since I bought my iPhone 6+. The reading app on my iPhone (free from Amazon/iTunes) provides a similar level of reading experience, and it obviates the need for carrying around an extra gadget.