The Cubs, Bears and Bulls all get amazing attendance no matter how bad they are. Sox and Blackhawks get good attendance but not when they are horrible. There was a time living there mabe 10-12 years ago when the Bulls and Blackhawks were dead last in both leagues, Bulls were somehow selling out and Blackhawks were giving away free tickets.
Chicago is probably closer to a two franchise city than a one franchise city for NBA, MLB and NFL. If the Bulls didn't have the Jordan legacy I think they'd need to win. People from around the country/world come and want to see where MJ played. Bears tickets will go for double or triple face value when the team is garbage.