Here's an idea for a comic, another TNG reference. A bit more serious, but it could be interesting: what if Twilight dies by some means, and runs into Discord, who claims to be Fausticorn (Pony equivalent to God) or something along those lines. Like with Picard, Twi is shown what her life would be like if she never left Canterlot, never met her friends, and never became the Bearer of Magic. Might have to leave out the Nightmare Moon thing or the world would be covered in eternal night without anypony around to stop her. Either that or someone else came the Bearer of Magic.