You know what? I think she should have married Draco.
(I have no idea where that came from. I don't usually do "ships." But somehow, Romilda Vane and Draco just feels so right -- the ruthless, ambitious, sneaky, social-climbing Gryffindor, and the Slytherin looking for redemption in a post-Voldemort world...)
Okay, so, canonically, not possible. But I could totally see her marrying some other wealthy Slytherin for similar reasons. (She gets a rich, high-status husband, he gets a wife who boosts his "I am not a former Death Eater! Really! Look, I married a Gryffindor!" cred.)