People, do you realize how much they would have to pay ScarJo to do a solo Black Widow movie? And Marvel is cheap. Like hella cheap. The only reason they can afford RDJr is because his character is in a costume with a mask for a huge portion of every movie. That person in the costume is not RDJr. If they made a Black Widow movie - a character with no mask where the actress cast would have to be in every scene - they would have to recast it.