Spoiler alert, if you haven't played conquest, and don't want spoilers, don't read on.
I think permadeath is needed for the series. It does change the strategy on how to keep everyone alive, but there could be an alternative. In conquest, the chapter that allowed one to get Gunter could provide such. He "died" by falling into the bottomless canyon. If a character died, and one could go into an underworld to save them, then that could be a way to save them. But, I think that would be avoided because of the opportunity for infinite grinding. So, maybe if there was some sort of item that allowed access into an underworld, to save someone, that would work.
I think if the game was to have children then this could be an alternative to their child's paralogue.