As soon as the first Avengers movie was released, everybody started talking about a spin-off featuring Black Widow. The character’s backstory was too interesting to be left without a standalone flick. However, as the fans said, her solo flick would also feature another Avenger, one who also had no superpowers. Obviously, that other Avenger was Hawkeye, who was nobody's favorite MCU superhero for so long.
There’s even a line in The Avengers that could have served as the entire premise for this spin-off movie: This is just like Budapest all over again.
But nothing really happened. And, as the years passed by, people started talking just about a Black Widow movie. Last year, even Kevin Feige said that the studio is committed to making such a movie (but we believe that it won't happen, since by the time the Infinity War ends, it will be too late).
Actor Jeremy Renner is still available for such a project. As he said in a recent interview, if the opportunity presented itself, he would join Scarlett Johansson in a spin-off:
I always thought it would make sense early on to do a Hawkeye/Widow movie because they're quite similar. They don't have powers, have high skill sets, and have history together. But I don't think there are any discussions about that happening. I'd love to do it, though (via CBM).
That's not too optimistic, isn't it? And it contradicts what Feige said (of course, maybe Feige is considering recasting the characters).
Nonetheless, such a movie could happen further down the line, in the Fourth Phase of the MCU. If Thanos used the Infinity Gauntlet, we could rewrite history. So who knows?
Jeremy Renner’s next MCU appearance will be in 2018, in Avengers: Infinity War.