Ubisoft should take all their Assassin's creed tech and just make a bunch of period pieces.
None of the games will say Assassin's creed on the box. They'll all have different names, but they'll all look, feel, and control like a AC game.
I'd love if they made a game where your a ninja in Sengoku era japan. You take orders form someone like Oda Nobonoga or  Hojo Ujiyasu.
Instead of being friends with DaVinchi your pals with Kotoro Fuma. If it had the same great voice acting, visuals, controls, historic figures It'd be pretty great.
Then they don't stop there, they make a french revolution game, American revolution, The Saboteur 2, dark ages England, I think that all would be great.
The only thing is everyone will say "Their milking it to death wah wah wah." 
On a side note I think AC:brotherhood has the best voice acting I've ever heard. All the lines are delivered amazingly well.