I do think that studios are a beat weary of female heroes. I think the same thing for minority superheroes. I think they see the numbers and think that because Catwoman and Elektra, for example didnt do that well financially or critically that there is no interest in female heroes. I think they also believe that young boys won't go see a female hero. But here's a little thing about that, in regards to a TV show Legend of Korra with a female lead.
I think some female heroes, especially Wonder Woman could be really popular if they make a good film.
i think Wonder Woman would have to be a spinoff to a "great" Justice League film to which Wonder Woman herself would have to be an absolute
stand out in that film, such to have a big fan base demanding a wonder woman spinoff film. But the director would just have to make Wonder Woman really unique and stand out to get that demand.
If it's done right and strong - i think Storm might be an attraction right off another great Xmen spinoff (Xmen: Class 2?) ,,,, But they would have to be add intriguing elements (racial civil rights, her deep phobia for closed-in quarters, Xavier rescuing and recruiting her...maybe include appearances by king T'Chaka aka the Black Panther as well as Shadow King.
Elektra was done just so horribly. If the fans and critics would have received a good enough return investment buzz, then word of mouth
could have got a sequel (despite many not being fond of Ben Afflick's Daredevil)
Black Widow is best fit with the Avengers group. Ditto with Ms.Marvel.
SpiderWoman would be an awful choice. (i was never interested in her comics anyway) Mockingbird cameo appearance in a future Avengers film.
movies like Resident Evil and maybe Salt ( there's strong talk of a sequel)
seems to feature strong female star roles and proving IF IT"S APPEALING AND DONE RIGHT, they can draw attention to an audience.
i have a feeling that Anne Hathaway's Catwoman is going to get a spinoff. Although she struck me more of as a BAT-GIRL rather than a Catwoman.
Would director Christopher Nolan be interested ? Or is he totally done with anything Batman-oriented? Stay tune to the director that takes this tight rope project on.