I know, It's kind of weird that Wintertusk hasn't even come out on real realm yet and I'm already thinking of future worlds. But I was just checking out the Wizard101 website, when I saw the map of the spiral. Now if you follow the line, it hits every world in order. Once it hits every world Wizard City through Celestia, the line loops back around and hits Grizzleheim, Marleybone, Mooshu, and Dragonspyre again. Now we know that Wintertusk is an expansion of Grizzleheim, so could it be that KI is simply making the next worlds expansions of the previous worlds? Think about it. Let's go in order of the worlds. After GH is MB. Look at it all of those pipes, could the expansion of marleybone be in the many waterworks and sewers of the city? Or it could be Marleybone at ground level, instead of the rooftops. It could even be Marleybone during the day!
Next world is Mooshu. World map please! Surrounding Mooshu you can see many mountains surrounding