Don't worry, I don't have any insider information! I just got to thinking, in only a year and half, we've gone from having a desert, forest, imperial station, and scum buildings, to where we are now with the iconic cantina, star destroyer bridge, snow plains, Echo Base, and Cloud City. I suspect that Imperial Assault will continue on its course of success (SW Insider just ranked it #3 for best Star Wars tabletop games of all time; beating out Armada in #4!). But my question for you is if we were to only get one more expansion what would it be? Would it be a large expansion potentially adding a new type of terrain (like desert, snow, scum building), or would it be a small expansion expanding upon what we already have (TS gave us more desert and Imp base, BG gives us more indoor tiles)? Where would it take place? The plains and streets of Lothal? The halls and rooms of Jabba's Palace? The catwalks of Nar Shadaa? The ash and lava of Sullust? What would it be?
My first choice would be a small box Kashyyyk; complete with treetop villages.
My second choice would be a big box Kamino; the walkways, platforms, and cloning facilities would be an amazing back drop for a campaign as the rebellion desperately attempts to halt the Empire.
Well these are my picks!

