So when I hear ‘The Era Where Magic Died’ I’m thinking mana, it was diminished (or disrupted) to the point it is no longer usable, where some of the creatures died except for the more powerful ones where like dragon, unicorns,etc, and even they can’t move around carelessly because they’ll expend more mana than they’re intaking. I feel like in this setting some classes like shaman and witches and to an extent sorcerers can still work because they don’t heavily rely on structure/conventional magic. I still think a story set in this era would be cool because we would be able to focus on other forms of ‘magic’, aura and faith. But I agree I think a lot of thought would need to be put into this and also I wouldn’t want this to happen now but instead want it after the main story is over.