The book is going to have a print run and is available for pre-order right now! It's being published by No Starch Press. The hardcover, however, is a mock-up, it will be a flexi-bound softcover.
Chapter 6 is also revamped (to use matter.js) and other chapters include expanded / revised examples and explanations. Chapter 10 was almost entirely re-written, Chapter 11 is new.
Just wanted to pop in and say hi here! Delighted to discover this thread, it's been quite the adventure trying to get this new version of the book finished. Happy to answer any questions about the book here! Thanks for the support and kind feedback.