Should Joel Schumacher had been allowed to make a Batman: Year One film?
Especially when it became apparent, that Michael Keaton didn't want to do what would become Batman Forever. I've often heard that when he was first hired to direct the next Batman film after Batman Returns, he really wanted to do an adaptation of the Year One story.
https://en.wikipedia.org/wiki/Batman:_Year_One
Batman Forever is in this weird area where it's not exactly a full blown reboot but it isn't exactly a true sequel. It's kind of like the James Bond movies, where you kind of have to take a broad strokes approach or view to its continuity.