First of all, the corrupted Gems that were healed were the ones that were bubbled. There still might be some that are out in the wild. Might be a material for a few one-off episodes.
Next, all the time White was ranting about how she is supposed to be flawless, the question in my mind was "supposed by who?" How DID Gems first arise? How did White Diamond happen? Is she a natural creature or was she created by someone else?
We might get more stories about various Gems visiting Earth and/or learning to live there, particularly the Off-Colors.
Then there's the Human Zoo. What is going to happen to it? Will the humans there be released on Earth? Would they even want to?