Okay, so since the Pokemon games left Japan, the new regions seem to have been chosen based on whether the area has a large, cosmopolitan city with worldwide importance. Unova based around Manhattan/NewYork, Kalos based around Paris/France. Future games will probably follow this trend, at least for a while. Which cities/regions do you want to see next/which ones do you think we're likely to see next?

If they hadn't just released Kalos, I would assume the next one would be London/UK, but I bet they don't do Europe 2 generations in a row.