Just so you know: spoilers ahead.
Okay, so the Sovereign were fairly toothless in Guardians of the Galaxy 2. They were more or less a plot device, and High Priestess Ayesha didn't get much time to chew the scenery or enjoy being a villain. But! According to director James Gunn, it sounds like she'll get another chance in the (technically theoretical but come on, we know it's gonna happen) Guardians of the Galaxy 3.
In a recent interview about GotG 2, IGN asked what the post-credits scene teasing the debut of Adam Warlock meant for Ayesha and if she would be returning in a future film.
Gunn responded, "I absolutely plan on bringing Elizabeth Debicki back. She actually is one of my favorite actors I've ever worked with. I think on this movie, between her, Pom Klementieff who plays Mantis, and Chris Sullivan who plays Taserface, they really were three of the best actors I've ever worked with and were all such a joy on this film to deal with. I'd love to deal with them again."
Ayesha isn't finished with the Guardians, and it doesn't sound like Gunn is finished with her. In the meantime, at least Marvel fans still have Spider-Man: Homecoming and Thor: Ragnarok to look forward to.