He was unlucky because he became available when our central trio was already made, Conte had no reason to make any changes and we were only focusing on the Premier League.
He is still only 22.. He'll play 35-40 matches for Stoke next season then we'll see. Cahill is 32, Azpilicueta's role in the squad is questionable, Rüdiger and Christensen might be flops, who knows.. He may come back stronger and more experienced.
Personally, I think Zouma will not fit into this 3-4-3 system. He is a beast, a great athlete, but he is very weak with the ball and choses the simpliest solution many times. Azpilicueta, Luiz, Christensen and Rüdiger are good passers and they are comfortable with the ball at their feet.