Well. Ok I don't really want to defend SE on this debacle, but there is some precedence.
1st: Delita is fatally stabbed (and fatally stabs) the princess. The royal progression is absolutely fubar. Ramza kills most of the possible people who would be interested in the throne. And then exits to an alternate dimension in order to free his sister. There is literally nobody else in charge from a player standpoint for the games to continue in the same universe. It's literally just rando families who kind of grasp power but are absolutely not some massive thing. Ramza literally kills several heads of house, while Delita does the rest.
2nd: During the buildup, you destabilize several countries. Which is f'n awesome. But doesn't make for great "and then what happens next" unless you establish what is going on politically. Which, sadly, FFT does.
3rd: Everyone who means anything is either in an alternate dimension or dead. That is a hard resurrection no matter how you spin it.