They could also use:
MCU:
America Chavez (Would be a good idea to ride that feminist and LGBT wave)
White Tiger (I could see a Netflix series for her)
Ghost Rider
Miles Morales (Most likely as he is the most popular but he is half black and half rican, so I don't know if that would appease them)
DCEU:
Blue Beetle
Kyle Rainer (Allegedly he is half Mexican but it has never been an actual part of his identity, I don't even think he speaks Spanish)
It's up to them to support, to buy their comics and build up hype. Black Panther may not have been A-List before the film in the mainstream but he was A-list in the comic world. Being a staple of the Illuminati, Avengers and key figures in events like Secret Wars.
They gotta support them.