I would love to see an organization of women operatives, led by a mysterious Dr. Cyber (not the computerized version), who would be a sort of anti-Amazonian group that would infiltrate modern society, using the power of women in a way that Diana wouldn't agree with. Cyber could be in league with an ancient/primordial power or perhaps an Olympian who would go against the Amazons of Themyscira and Diana. Perhaps a rogue Amazon? Someone who knew secrets of Hippolyte's or Diana's and tried to use them for more diabolical needs?
Maybe Diana could call on some of her sisters to join her in the outer world, too. A few extra Amazons living away from Themyscira who were inspired by Diana somehow? Just an idea.