An accompanying chart shows the two lines converging: a pale yellow (easily breached?) line for the print market, and a robust red line for the e-book market, rising at an impossibly audacious angle from 2008 to 2017.
The revolution from manuscript to printed book took centuries. From the looks of it, the digital revolution will not last as long. Could it happen in a generation?
If so, we who are living through it are left with spinning heads and two libraries: one that is real, one that is virtual.