Exploring Azeroth: Northrend has become available for pre-order. This latest installment is set to release in October, and is written by Alex Acks.
www.wowhead.com
Didn't expect them to do more, but this is awesome. I don't own any other Warcraft books, but the Exploring Azeroth series has been pretty great, I have both the Eastern Kingdoms and Kalimdor hardcover ones. I highly recommend them, lovely artwork, and it tells a story from the PoV of a character/companions and their notes on their expedition/travels through the continent and exploring the history, secrets, treasures, peoples, of the lands.
They're pretty cheap (20-23 euro for each hardcover here in Germany) so I recommend them to anyone curious.
World of Warcraft: Exploring Azeroth - Kalimdor : Copeland, Sean: Amazon.de: Books
www.amazon.de
The Kalimdor one had lore mistakes (tbh this is Warcraft lol) but it was still pretty good and worth it just for the artwork alone