Yeah, I wasn't expecting it at all either. They just released the first major DLC for III and they've already announced the next game? Seems a little early.
They have released more info since the trailer came out, and the game will have more historically accurate content. They also said only 1/4 of the game takes place on ships, so there will still be plenty of buildings. As for CoD syndrome, assassin's creed wont get that because of how in depth the story line is, it's not just a war game like CoD it actually has some substance to it. So overall this game might not be their best but it will still be a great game.
