The correct answer is, yes it would throw a wrench in the advertising, but it's not the end of the world. You're talking mostly the between quarter breaks and halftime. Furthermore, this kind of thing is not uncommon. There's been more than one occasion in recent years where CBS has had to move US Open tennis coverage into Monday, totally screwing local affiliates schedules, for instance. You just have to deal with it. There are countless examples of things like this, mostly with sporting events due to the unpredictable nature of them.
In this particular situation, FOX local coverage would only been in the KC and Charlotte markets most likely on Monday night, while the rest of the country is unaffected and gets regular FOX programming. Is that an ideal situation? No it is not. But neither is your starting middle linebacker driving up to the team practice facility and blowing his freaking head off.