You don't need constantly escalating stakes to tell a good story. A smaller-scale story about, say, Meracydia or the New World could still be super enjoyable. We've been to the First, but what about the others (that haven't already been Rejoined)? We know there's some effort being put into possibly trying to restore the Thirteenth, and there's even other stuff like the Ea they introduced that could prove interesting. Sure we're not saving the entire universe, but we can still save a continent, or a single city, and still find it fulfilling if we care about the people.