Black Widow has been one of the more illusive characters in the Marvel Cinematic Universe. She has no franchise of her own, despite Scarlett Johansen’s pleas for one, but pops into the major movies of the MCU. It has been confirmed that she will reappear for Captain America: Civil War.
Anthony Russo, one of the directors of the film, said this:
“We’ve been preparing for the movie since the last one debuted last year. So, we’ve been working on it for a long time now. We’re very happy how it’s coming along. Captain America 3 is gonna be called Captain America: Civil War and it’s going to star Chris Evans, Scarlett Johansson will be back, Winter Soldier [Sebastian Stan] will be back, and Robert Downey Jr. as Iron Man will also be joining us in the next film…The new element in this film is that Captain America and Iron Man get into a fight with each other.”
This shoots down the theory that Black Widow may be dying in Age of Ultron, unless her roll is more in flash backs (with a big name actress, I highly doubt that). Fans, for the most part, like Black Widow and will happy to see her return. It’s unclear what her roll will be in Age of Ultron and there’s rumors of a Hulk romance. For now, only time will tell.