No doubt, armed law abiding citizens will drive crime down if Chicago actually gets ccw, but I’m not sure I beleive that will happen to any great extent. BTW, Detroit has ccw and many armed citizens that kill criminals regularily, yet they still have very high crime rates.
Detroit is kind of a special case, because it had a huge exodus of good citizens, leaving it in a position of collapse. Chicago is going to need a giant bucket of popcorn.