For anyone that keeps up with the supplementary lore materials, the Book of Adria, which follows its predecessors like the Book of Cain and Book of Tyrael, has been delayed for the masses, but they did some sketchy stuff and are bringing some to the con ahead of schedule. The actual release date of the book will come sometime after the con, hopefully "soon" after.
Hey everyone! Wanted to update you all on Book of Adria. Bottom line first: The release date has been pushed back. I don’t have an exact ETA yet, but the copies are en route from the printer and we hope to announce the availability date soon. It will be after BlizzCon. Some good news: We will have the book available AT BlizzCon! Our products team is going to great lengths to make sure we get some early copies there. @Burnzerker and I should be on hand for signings, too!
~Robert Brooks, Blizzard Writer
Also, just spitballing here, but I doubt they'll be in the Gear Store or they'd be open to virtual attendees which could conflict with a publishing/release agreement? It might be its own separate thing at the con. (Again, just putting that out there, I have no idea.)