After Battle of Heart and Mind
Ok. So I've seen a bunch of people saying that after battle of heart and minds theres not much else the show can do. BUT THATS SO FAR FROM TRUE!
We now have a good relationship between the crystal gems and the diamonds. The diamonds clearly plan on leaving earth as it is. So with homeworld and earth on good terms, steven and the gems can go back and forth without any threat to them. So this may cause the homdworld warp to be fixed again, allowing direct travel between esrth and homeworld not just for the crystal gems, but the corrupted/healed gems too! Imagine adventures on homeworld or even other diamond colonies! More gem culture, more homeworld weirdness, a more alien vibe! Not only that but we have all the healed gems! New gems to meet and interact with, some of which are from the rebellion!
Not only that but im positive that there are more corrupted gems out there so we have plenty of monsters still waiting for us. With the revival of the homeworld warp we may also see some gem structured on earth being repaired(like a brand new lunar sea spire!). The Steven Universe movie clearly has a gem antagonist, so this kind of furthers the idea of homeworld adventures.
Another popular theory I've seen is the idea that the crystal gems will face the species that created the diamonds and gems in general. Either way I'm extremely excited since the introduction of stevens fusions means we will definitely see them again! Theres so much potential now and it makes me SO EXCITED