Open world AC type is really bad. There really isnt anything(fun) to do in AC outside of missions(Black Flag not included). Make the world like in Dishonored and its epic. Flesh out the world so well that you dont even notice the borders and it actually feels exciting every time you take a different path to an objective. ACs only excuse to even be open world anymore, is so that you could notice the architecture. If you are that kind of tourist.