1 of the very few funny female characters on The Simpsons. I wonder if they will find a sound-alike to replace her or if they'll just exclude her like they did with Hutz/McClure when Phil Hartman died. Those were just recurring characters though, easy to leave out. Might be a bit tougher to suddenly leave Edna out of the script.
That sucks. What's odd is The Simpsons announced they were going to kill off one of their characters this year and Mrs. Krabappel was heavily rumored to be the one. The show released a statement saying Krabappel wasn't going to be the one but I wonder if they'll change course now. Maybe keep that character around and just use this as a way to have a classy send off.