The program for last weekend's JordanCon event contained a preview of the U.S. Tor Books edition book cover for TOWERS OF MIDNIGHT. It features artwork from Darryl K Sweet, the same artist who has done the U.S. cover art since The Eye of the World.
Important note: As the image below clearly states, this will not be the final artwork for the cover. This was an early version that will have changes made to it. Although Brandon Sanderson and other members of "Team Jordan" wouldn't say specifically what might change, they did say there were clearly little mistakes in details, as well as at least one "major mistake." (Not to mention a spelling error!)
Here's the scan from the program:
Tor Books intends to have Darryl K. Sweet complete the final two book covers for TOWERS OF MIDNIGHT and A MEMORY OF LIGHT. Once the series is complete, they will likely develop a plan to release a second edition of each book in the series with new cover art. One of the goals of releasing the eBooks with new art is to experiment with different artists and styles to see what fits for the series, and the fans.
Feel free to discuss the content of the image in the comments section. Beware of spoilers, however, as it will be hard to avoid them!