[WARNING – This article may contain SPOILERS for Spider-Man: Homecoming.]
Every since Scarlett Johansson's Black Widow first appeared in the Marvel Cinematic Universe way back in Iron Man 2, fans have been clamoring for her to have her own solo movie. While it's clear now that the first solo female superhero-led MCU movie will be 2019's Captain Marvel starring Brie Larson, that doesn't mean fans won't be seeing more of Black Widow.
Avengers and Avengers: Age of Ultron director Joss Whedon recently said he would return to the director's chair for Marvel should the opportunity for a Black Widow solo movie present itself, and Johansson herself said that Black Widow is her favorite role. While neither of those things means that Black Widow is certain to get her own movie, she will at the very least be making appearances in other MCU movies in the near future.
One such movie she may appear in is the Marvel/Sony collaboration Spider-Man: Homecoming, wherein Tom Holland will be reprising his role as Peter Parker from this year's Captain America: Civil War. Comic Book claims that it received a tip about Johansson filming material for Homecoming recently; and now, there's a tweet from @AtlantaFilming (which was first picked up by Screen Geek), suggesting that Johansson was in town. Given that Homecoming is currently being filmed in Atlanta, Johansson's presence there would either be a big coincidence or an indicator that Black Widow will be dropping by for an appearance in the wallcrawler's solo movie.
This is not any sort of official confirmation that Black Widow will be in Spider-Man: Homecoming, of course, especially considering that so far no other outlets are corroborating the report of Johansson's Atlanta sighting. Still, it seems like a rumor that is particularly likely to be true given Marvel's propensity for crossing its characters over between movies. It's already confirmed that Tony Stark will be making an appearance in the Spider-Man movie, which puts to rest any fears that the movie being partially produced by Sony would keep other MCU characters from appearing in it.
Spider-Man: Homecoming will be one of three MCU movies to be released in 2017, along with Guardians of the Galaxy Vol. 2 and Thor: Ragnarok. Given that both of those movies will be primarily off-Earth affairs, it seems unlikely that Black Widow will make an appearance in either of them. For fans of the character, though, there is still a strong possibility that they will get at least one chance to see her when Tom Holland's Spider-Man makes his solo movie debut.
Doctor Strange opens November 4, 2016; Guardians of the Galaxy Vol. 2 – May 5, 2017; Spider-Man: Homecoming– July 7, 2017; Thor: Ragnarok – November 3, 2017; Black Panther – February 16, 2018; Avengers: Infinity War – May 4, 2018; Ant-Man and the Wasp – July 6, 2018; Captain Marvel– March 8, 2019; Avengers 4 – May 3, 2019; and as-yet untitled Marvel movies on July 12, 2019, and on May 1, July 10, and November 6 in 2020.