Costume design, unless the Academy falls in love with some period piece.
Honestly though, I think it's got a shot at a best picture nomination.
Noooooo way.
I mean, it has the cultural clout but, purely on its merit as a film, it is just a blockbuster. "The Dark Knight" got nominations because it succeeded as a film first and as a superhero film second. And keep in mind, it got nominated in a year where the Academy was scared they were losing their audience because they were out of touch with the general populace. Ledger got the award for "TDK" largely because he passed after filming and his history of phenomenal performances. Had Ledger lived, I don't think the Academy would have given it to him.
Black Panther, as a film, does fall into the same Marvel Studios story trappings, most notably the finale is a CGI slugfest with some kind of objective that must be completed before time is up. The acting is fine, but it doesn't fit the Oscar's wheelhouse on character-focused drama fueling the plot instead of action. Plus, that's to say nothing of the ceremony's very real bias against any blockbuster action film winning the major awards (see: "Dunkirk" and "BR2049".)
I think Hannah Beechler will rightly get nominated for production design, and the team behind costumes for the costumes award. After that, Ludwig might get nominated for Soundtrack, but other than that, it's going to be locked out.