Scarlett Johansson has demonstrated in movies like Avengers: Age of Ultron that she has the chops for a solo movie. By Jay Maidment. ©Marvel 2015 Avengers and Avengers: Age of Ultron director Joss Whedon used the Black Widow (Scarlett Johansson) for several emotional story beats. By Jay Maidment. ©Marvel 2015 Looking at this concept art for Avengers: Age of Ultron, it’s not hard to imagine a Blac…