I agree he should be starting this year. I have no doubts about his ability, I am more concerned with Chiellini. The latter tends to have fairly poor in the beginning of the season and grow more as the season goes. Hopefully, we get a strong RB to help the defense gel.
He was better/more reliable and more consistent than both Barza and Benatia last season. Chiellini and Bonucci should be the starting duo, with Benatia and Barza ready to come in if/when necessary. No point in splashing 40+ on someone like Manolas, especially with Caldara coming in next season at the latest.