i honestly don't see how feudal japan could work in the AC universe.
would we be backstabbing templar samurais as some asian assassin or something? i'm not even sure how an asian ancestor would even work in desmond's bloodline, unless his ancestors have been "getting busy" across the world, which would be kind of difficult in the time period the game's historical periods are set in.
idk, they could make it work somehow. In my opinion, Egypt is an easy way out for them since they could just put the "Challenge maps" inside pyramids, so this might be most likely to happen since they love those challenge maps.
AC3's setting aside, I just can't wait for this game to move closer to the World War 2 timeline from that interview a couple of years back, the guy hinted AC could move towards a world war setting someday.
This interview actually
The game franchise focuses on Desmond and his bloodline, I really don't ever see the focus straying away from that. Maybe after Desmond's plot concludes.