Maybe theyll do Shogun as the rehash expansion pack? Theyll need a new map to represent Japan, but that would be less work than the Americas. Same with cultural voice packs and symbols etc etc. Theyve already done the historical research for the first game. Time saved there. And the unit/building tech trees are less time consuming than what would be required for doing a New World option. It would be relatively quicker than a lot of other options and would get all the rehashes out of the way.