What is Walter Isaacson’s next “big writing project”?

Last week, Walter Isaacson surprised everyone by resigning as the Chairman of the Broadcasting Board of Governors.  Why?  Because, according to Isaacson, he did not have the time because he had a “big writing project” coming up.
What is this project?  According to In the Loop‘s Emily Heil, Isaacson will “chronicle the history of the digital age, from the famous Ada Byron Lovelace to the present.”