Warner Brothers planned on making Green Lantern a franchise with plenty of sequels, so it would make sense for the Carol Ferris character played by Blake Lively to become Star Sapphire at some point.
Lively has (sort of ) confirmed that Carol Ferris' alter ego Star Sapphire will pop up in the future. In a recent interview she said, "If this movie is successful and we did a few more films, I'm pretty confident that Star Sapphire would show up." [Blastr]
Considering the movie opened with an estimated $53 million box office compared to its $350 million cost ($200 million for the movie and $150 million on marketing), the prospects of a sequel aren't looking as good as they did when Lively was interviewed. Nonetheless, this story serves as a great excuse to post a bunch of borderline-NSFW Star Sapphire cosplay pictures. So let it be written, so let it be done:
Wait, that's not Star Sapphire cosplay. That's just Blake Lively wearing purple.