Assassin's Creed III creative director Alex Hutchinson doesn't like your suggestions for the series signature historical settings. Speaking with OXM, Hutchinson said he thought many of the popular rumors about ACIII's new locale would make for absolutely terrible games.
"People on the Internet suggest the most boring settings," said Hutchinson. "The three most wanted are WWII, feudal Japan and Egypt. They're kind of the three worst settings for an AC game."
Assassin's Creed III, as you've probably heard, is set in New York and Boston during the American Revolution, another popular rumored AC backdrop.
Personally, I think it would be bad form to start going back in time again, so I understand not wanting to do Ancient Egypt. World War II, aside from being done to death, relies a little too heavily on guns to make sense in the series' current mechanical framework.
I wouldn't rule Japan out though. Not feudal Japan - ninjas and samurai are too easy. Let's move the series forward to the 19th century, when Japanese culture became obsessed with westernization. (If you're not familiar, think of The Last Samurai)
Then again, just because a place and time make sense in the story's framework doesn't mean it will make for a great game,. Hutchinson pointed out as much when he explained why Philadelphia was cut from the Assassin's Creed III landscape.
If not the American Revolution, where would you want to see the Assassins and Templars duking it out?