4) The Simpsons
Having told 27 years’ worth of episodes that reset by the time of the end credits, The Simpsons has never had much in way of overarching story arcs. But this could have changed if two planned twists, conceived way back at the character designing stage, had actually gone ahead.
Ever wondered why Krusty and Homer look alike? Well, this was because creator Matt Groening’s original idea was for Krusty to have been revealed as Homer in disguise at some point. The joke being that Bart’s hero was actually his deadbeat dad. However, once Krusty garnered his own popularity, this was dropped.
Similarly, there was also a reason for Marge’s ridiculously large beehive hair-do to start with. Initially, the idea was to reveal that Marge had rabbit ears hidden under there. Presumably, this was ditched when everyone realized how weird an idea that was.