The Men in Black — 21 Jump Street movie has a title and a director.
During its panel at CinemaCon on Tuesday, Sony announced that the movie would be called MIB 23, according to io9, and would definitely combine both movie universes. Sony didn't announce if 21 Jump Street stars Jonah Hill and Channing Tatum would be returning for the film, but it looks likely.
Will Smith and Tommy Lee Jones have already said they aren't interested in reprising their Men in Black roles for the new movie. Whether or not they make a cameo appearance, much like Johnny Depp and Peter DeLuise did in the original 21 Jump Street, is also uncertain.
James Bobin, who directed Muppets Most Wanted, is reportedly attached to the project. Sony hasn't announced when the movie would begin production, or when people can expect to see it in theaters, but it is definitely happening.
Who, exactly, asked for this crossover is still being determined.