The Hollywood Reporter has learned that Lupita Nyong'o is in talks to join Ryan Coogler's Black Panther, and considering Lupita's run of Disney movies - Star Wars, Jungle Book, Queen of Katwe - I bet the studio has a real sweetheart deal in place for her. I bet this goes through.
The report says that she would be playing T'Challa's 'love interest,' but who could that be? There are three possibilities that leap off the pages of the comics:
Monica Lynn is an American singer who became Black Panther's girlfriend for a period (they met when she saved his life), going so far as to move in with him at the royal palace in Wakanda and to become engaged to him. It didn't work out. This character seems sort of unlikely for a couple of reasons, the main one being that she's the standard 'girlfriend of the hero' character and I hope that Marvel is moving past that trope.
Okoye is a member of the Dora Milaje, once the ceremonial wives of the king of Wakanda but since repurposed as a group of badass bodyguards. You saw a Dora Milaje in Captain America: Civil War - the tough bald lady who got in Black Widow's face in the garage. In the comics Okoye is in love with T'Challa, but he doesn't return her affection. Still, it seems like the movie would need to have a love interest who kicks ass - Okoye would fit that bill.
Finally, T'Challa once married Storm. The problem here, of course, is that Storm belongs to Fox, and while I think Lupita would make a killer Ororo, that likely won't be happening. But could there be another heroine who fills that role? The truth is that the Marvel Universe is low on black female superheroes, but there is a character I'm dying to see onscreen: Monica Rambeau. She's MY Captain Marvel, although if she were to show up in the MCU she would probably be called Photon or Spectrum, her other hero names. She's a tough, capable leader whose body turns into light and who can blast fools with her light powers. She's really cool and could hold her own against a king.
If I were a betting man I would place money on Okoye or some variation of that character - a member of the Dora Milaje who is involved in a will they/won't they relationship with her king, perhaps one that she doesn't want to get into due to the Dora Milaje's past as a concubine group. That's good tension, and it doesn't have to have a cheap payoff. Also, the better Marvel love interests have been very capable women who support the main hero while not easily or quickly falling into the boning buddies role - see Peggy Carter and Pepper Pots, for example.
But man, what if they did some negotation magic and Lupita was Storm? I'd die.