I think, given the success of Game of Thrones, a Westeros world could generate a lot of interest in the engine.
People would be talking about it heaps, and making models to fill the world. If I remember correctly there was a Minecraft version built, so there must be height-map data out there.
The earth is amazing and should be the main focus at this stage, but there is also Middle-Earth, so why not Westeros? I would bet a fair few people would buy the engine to explore that, so it could help with funding.
Just a thought.