I sure hope Nomura isn't aiming for an over arching, multi-complex story, because he failed hard. Mind you, I don't mean that the story isn't thought provoking. Really, there is only 3 or 4 ways to look at the story progression: Darkness fucks [parasitic bomb] up, Friends and allies become lost in darkness, Light overcomes darkness and the hero saves the day. That's all it's been from (chronologically) BBS to KH2/Coded. From that core perspective, they add FF, Disney and now TWEWY characters and worlds to sweeten the entertainment factor.
The battle between Light and Darkness is obviously an age-old thing, and the KH series is by no means the best or over-complex take on the topic. But I hope SE keeps in mind, first and foremost, it is a story about a boy and his Keyblade. Fighting for his friends. Simple and fun. It's supposed to be a average, pick-up-and play series with a simple storyline. And I feel that lately they have been trying to needlessly add "filler" darkness and "lost memory" ploys to try and deepen the series. If they want to go any deeper, just focus on MX's "resurrection", have Sora (and Riku) kick his ass, and done.
Hell, not even an average Final Fantasy game gets terribly deep.