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.
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.
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.
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.