Injustice’s mechanics and storytelling potential is something that could apply to almost all the DC, but especially the “mundane” super families. Once you can establish enough suspension of disbelief to allow Wonder Woman to slug it out with Harley Quinn in a fighting game, and tell a story around it that people can stayed engaged with, you can do practically anything with the characters more traditionally suited for fighting games.
It’s just a matter of roster space and exposure, two areas where Cass and Shiva have stiff competition and a few disadvantages just because they’re still more comic-specific characters than multi-media ones.
It would be *awesome*, though.
Interestingly, I think that the Arkham games, or at least their likely successors, would maybe have a more immediately realized potential for introducing a version of Cass that stands out; the way those games managed to specialize Bats, Nightwing, Robin, and Catwoman tells me they could probably do something very similar with Cass.
She strikes me as a character you could play as almost a “glass-cannon” melee specialist in those games; very few gadgets, perhaps less health, but utterly monstrous combo and free flow abilities that start after only a few hits.