I have a few:
- Queen Serenity was a Sailor Guardian before she was queen of the Silver Millennium, but instead of being a guardian of the Moon, she protected the planet Theia, named after
a theoretical ancient planet that collided with an early Earth which resulted in the formation of the Moon.
- In the same way there exists a Chaos and Sailor Chaos, Sailor Cosmos is a potential incarnation of the goddess Cosmos, the creator of the Milky Way and potentially the entire universe. In the original anime, Sailor Galaxia is an incarnation of the goddess Cosmos instead, which is why her starseed takes on the form of Chibi Chibi. Cosmos could be seen as the Sailor Moon metaverse's equivalent to God and I imagine she would be as incorporeal as Chaos, appearing as an all encompassing glowing light.
- Sailor Chibi Moon's adventures after the Stars arc will revolve around a lot more time travel to different periods of time, and perhaps even different timelines. She will also have to deal with the potential paradoxes born from her repeated vists to the past manifesting as new enemies.
- Chronos is a deity similar to Chaos and Cosmos, with Cosmos representing Space, Chronos representing Time and Chaos representing the absence of both. In the same way that Sailor Moon will one day become Sailor Cosmos, Sailor Chibi Moon will eventually become Sailor Chronos and embody the aspect of time.
- Similar to how Chibi-Usa has connections to both the Earth and the Moon because of her parents, Prince Endymion's mother is connected to the Earth and his father is connected to the Sun, which is why in the Dream arc he is referred to as the
"The Prince of Earth, protected by the Sun.", has a GOLDEN Crystal and his equivalent of a Luna-like familiar in Helios... Who also has a solar connection. It also offers an explanation of why we've never seen a Sailor Earth OR Sailor Sun, since in essence Mamoru could potentially tick both boxes.
- Chibi-Usa will have twins in the future and they will have a Sun and Moon motif when they transform into Sailor Guardians, referencing Apollo and Artemis.