I would also stop watching if Stewie or Brian left. I mean, they're the only intelligent main characters. Sure, there's Lois who I believe is very intelligent and knowledgeable, but the show loves poking fun at outdated women stereotypes so the viewer may be led into thinking that Lois is just a 'thing,' not a person. There is always complications shown with almost all female characters-- Meg, Jillian, Diane, Loretta...