They do struggle with the fact that the genre Star Wars draws on the most, 30s "planetary romance", was always made up of eclectic, tossed off stories that didn't hang together properly. That's why A New Hope has that fresh first album feeling to it, but the elements it introduces are a challenge to build on.
JJ Abrams being involved in the new ones was always a bit of a bad sign. He's a very competent man with zero fidelity to art or any transcendent vision.
If I were Disney I'd be pinning millions on the writing for Rian Johnson's trilogy—the Star Wars universe needs a lot of quality world-building in a hurry, and so much of the "gimmick planet" / "gimmick character" (Canto Bight, Camino, Maz Kanata, Boba Fett, Count Dooku) inserts in both the prequels and the more recent stuff has been woeful. The settings are wafer thin, and the characters are abominable.
A quest storyline could work if the casting were up to the mark of Boyega, Ridley, Isaac, Driver etc. Give it a bit of scaffolding.
But I do think Star Wars IX is likely to have a quality plot and finale.