Hey, I'm thinking of a wild scenario. In early dev, the hero (Cloud/Zack) & the heroine (Aerith/Tifa) is basically one character in concept, with ancient and seeking to promise land is always the core of the plot. Now, in final dev, by bringing Zack alive, what would we probably get? Two timelines, dual heroes, dual heroines. And what would happen in each timeline?
So, what if.....
#1 Zerith alive, Cloti dies, Sephiroth is back to sane. (as alternative story)
#2 Cloti alive, Zerith dies, Sephiroth is destroyed. (as the original one-AC-DC)
At one point, the timeline must intersect, probably in the event when Aerith would die in both timelines 'cause that's what player wanna change. And player decision would determine which ending to get above. The future is a blank page. I still can't explain how the alternative scenario would work... but it's fair we'll get different loss & tragedy. Both can be perceived as bad & good ending differently. Normally, people would go with original story and the game would be likely default to that, even if both Zack & Aerith survive.... we'd be still directed to get ending #2.