They have to do Japan...eventually
Look, with Tenchu mostly dead, here I come. HOT.
The next Assassin's Creed should be set in Japan, right? So we agree.
Wait, you want Assassin's Creed Revelations 2? Who retreads the same places you've been to before? You want another Rome game? We have different priorities, my friend!
But for real, people have been craving an Assassin's Creed set in Japan basically since the the series is out. And in order of release we got: Holy Land, Italy, Spain (discovery), Istanbul, America, Caribbean, Your country, London, Egypt, Greece and some parts of Europe. In some cases, you can add parallel stories to surrounding regions, such as New Orleans at Liberation, etc. I mean, we got China, India, and Russia, all through the Chronicles 2.5D spinoff! But these weren't full open worlds and could be revisited one day.
Even in derivative form, we didn't get Japan. Feudal Japan, notice. I should clarify this obvious wish, if you couldn't tell from the Tenchu header. I mean, I'm totally willing to admit that I just want more Tenchu in my life. I mean...it's still kinda via Shinobido (even though the last game was 10 years ago) and projects like Aragami itchy scratches.
But a really well-made, fully-budgeted game with historical characters could be a home run, especially after how well Sucker Punch handled it with Ghost of Tsushima. If Ubisoft Didn't Plan A Feudal Japan Assassin Creed, They probably put on their radar somewhere after Tsushima was released to critical and commercial acclaim.
As long as they sell, there will be more AC games. We just got a Viking one, and despite its flaws, it sold out and was generally well received. The question is... when and where is the next one? The answers? “Soon” and “wherever they think will make them the most money”.