There are a lot of fans out there who would love to see a stand alone Black Widow movie. Marvel studio president Kevin Feige has admitted in previous interviews that the studio has been discussing ideas for a solo film, but that it also wouldn't happen anytime soon. When it does eventually happen, Game of Thrones director Neil Marshall would love to make it! In an interview with Vanity Fair, he said,
"I would love to do a Black Widow movie. That’s perfect, I would love to do that. That character is really interesting, she doesn’t have any superpowers, she just has extraordinary skills, and the world that she comes from, being this ex-K.G.B. assassin, I find that really fascinating, yeah."
As you already know, Scarlett Johansson‘s Black Widow doesn't have any superhuman powers. She's just a natural badass, and that's what Marshall says he likes about her.
"I think I’d like to do a big movie with a strong female lead, whether or not she would be a superhero. [...] I’m less interested in people with superpowers because I can’t identify with them. Very rarely do they get killed off, and when they do get killed off, chances are they’re going to be back… somehow. Yes, I’d love to do a big splashy movie with a great female lead, but it has to be someone I can believe in."
Black Widow has been such a great character in the Marvel Cinematic Universe, and I think there's a great story to tell with her. It's just a matter of finding the right story and time throw it into the mix of films.
I also think that Marshall would be a great director to develop the project. He's definitely the kind of director that Marvel would bring on board. Marshall's not a big, well-known director yet, but on top of Game of Thrones he has also directed The Descent, Centurion, and the pilot episode for NBC’s Constantine.