I'm going to go out on a limb and say this defense has a chance to be historically good. And it all starts with... drum roll... Mitchell Trubisky.
If Mitch makes the next progression he starts hitting those wide open receivers on the deep routes. That opens up everything from the screens, crossing routes and especially running game. This will give Nagy the ability to step on throats the way he wants, whether it be to score quickly to allow or D to pin its ears back or sustained drives to give them rest.
With Roquan and Mack getting a full training camp, Haha playing with a chip, Eddie being healthy and Floyd coming into his own, this D wow! The other players just need to play at their usual level. Just pray for Mitch and the health of this D.