Jon Peterson announced at The Playing at the World Facebook Page that the new edition of his book will be ready soon:
It has been something of an epic journey since 2012. Playing at the World returns shortly in its new MIT Press edition - or at least, the first volume does. Volume 1 contains the material that was in Chapters 1 and 5 of the 2012 edition; Volume 2 has the deep dives on setting, system, and character that occupied Chapters 2 through 4 of the 2012 edition. V2 is thicker and should appear in 2025. There's a lot of new material throughout, but, to me it's still the same book. Thanks to Erol Otus, there has been a substantial improvement in the cover(s).
I found the original edition a very comprehensive and detailed look at the history of our hobby and I look forward to seeing the new material he mentions. And having a cover by Erol Otus is an excellent choice!
-Havard