SU Theory to quench the Hiatus Thirst.
Ok so this is more like two theories that relate to each other:
1) Lapis leaves Earth for Good
In the SDCC Trailer, Lapis seems to be turning her back on Peridot and Steven, literally and metaphorically. The show has already addressed Lapis trying to find a better place on Earth to stay, it would be redundant to do again. This leads me to believe that Lapis is leaving Earth forever, or at least plans on it. This leads me in to my next theory.
2) Stevonnie crashes on a planet being terraformed
Stevonnie is seen crashlanding on some unknown planet that looks somewhat similar to Earth. They have no way of escaping unless Lars finds them. Basically, I believe that the planet that Stevonnie lands on is a planet being terriformed by Lapis’ making way for a new Homeworld colony. Our Lapis would easily fit in and could go about her life without ever worrying about Earth or the Crystal Gems again. Unless of course, a human that looks oddly like Steven and Connie lands on her hiding spot. Lapis wouldn’t leave Stevonnie to die so she escorts them back to Earth. If done correctly, we could get confirmation of how Gem colonies are created, other Lapis’ personalities, and gems at work (tbh we’ve only seen Pearls serve, besides that ll the gems have been deflecting from their natural purpose)