I think I recall one of the creators saying something like he doesn't think Asia is interesting enough for a AC game, and of course people were not happy. Maybe it will still happen.
By the way Japan and China are great, but Korea also has an interesting history and culture, and it would be more interesting to play because most people have already seen so much about China and Japan but so little about Korea.
For great inspiration I recommend they watch Korean TV show "Slave Hunters ( AKA Chuno)" it's about slave hunters who capture runaway slaves for money and the consequences of that, it has excellent fight scenes, AMAZING soundtrack, scenery and style with a deep historical political culture to get inspiration from including royalty and assassins. Actually in the game the main character could be a runaway slave to make things more interesting
OK post got too long.