It looks like the next set in the Architecture theme will be the United Nations Headquarters (21018). This set has a lot of creative details. The little Lego joysticks/levers for flagpoles, a technic brick for a fountain, and little Lego grill pieces set together for windows.
This years Architecture sets have all been great. With the Imperial Hotel (21017) and the Leaning Tower of Pisa (21015) being released so far, it will be interesting to see what else Lego will release this winter.
Big thanks to Flickr user motayan for posting the first photo.