This is another episode where anything can happen. We know it will have Steven hanging out with Buck Dewey, but really: you just can’t predict the twist on an episode that’s had such a mundane-sounding summary released. There will definitely be a twist, but it’s just too tough to guess what it will be.
Since this is the last season-one episode to air, we can rule out a new power and Peridot. Since the preview involves Greg giving guitar lessons, we can hope he shows up. Other than that, it’s Steven Universe—who knows what’s gonna happen?