One trope as old as the hills -- and one that many comic books and comic book shows have been criticized for employing over the years -- is to have a character from an underrepresented group (be it race, gender, or religion) exit a series in order to "make room" for another. At this point, most shows are conscious of the trope and avoid it, but that makes situations like the one DC's Legends of Tomorrow recently faced a potential target for criticism and jokes.