Yea hopefully they will make the AI a little tougher, you would like to think they have thought this through and will come up with some good mechanics for it.
On Black Flag you couldn't counter kill all of the enemies, which got rid of the one hit kill on everyone that was so prevalent in previous games. I actually thought the combat could be a little tough at some points on Black Flag, it's never massively hard, but it was more challenging that previous ones in the franchise.
Once you use darts / smoke bombs regularly it does make the game pretty easy, but a hell of a lot of fun