Personally I would love an Asia total war with an expansion focusing on Japan. There is a huge potential of variety in Asia that has yet to be fully explored.

The issue I think will be sales. Shogun was highly focused on an area that might not sell well enough for CA to devote an entire game to it. Devoted fans of the series would love this but would such a game bring in enough new fans? I am not so sure. Same thing with an Asia total war, will it expand their appeal more than another European/American period game.

I actually think we may see them move away from the huge campaign games toward a more narrow and directed period game. something like Road To The Revolution and NTW. This could mean smaller games but more frequent publishing. Focusing on wars that they think will sell well. I am not keen on the idea, but I do think it is possible.