4. Sideshow Bob
Sideshow Bob's bitter and often deadly grudge against Bart has stuck by the Simpsons family for 20 years now, and so the question is - when will it end? Well, the recent announcement seems like a golden opportunity. Kelsey Grammer's Emmy-winning performance as the character surely can't go on forever, and so it is very possible that next season could see a gripping Sideshow Bob-centric episode where he pays the ultimate sacrifice in order to redeem himself for his many terrible (attempted) acts. While I would be sad to see Sideshow Bob go, as he is without a doubt a fantastic character, there's only so many times you can see his many plans foiled without it starting to feel stale. After 20 years of failed murders, one final episode that sees Bob's demise may reach the emotional depth the series has failed to get to in recent years. Plus, due to the fact that he's hardly a regular member of The Simpsons' cast, but at the same time very recognisable, his death would be easy to carry on from but at the same time a high-profile event - something that would be good for The Simpsons' unremarkable ratings.