And once again, Kalinara wins by coming up with an idea that I would read the living shit out of:
Picture it: Green Arrow's in like China. Or Brazil. Some place cool like that and gets into a fight. And then suddenly, the old woman in the corner throws off her hat and it's Cassandra Cain! She'd be there for her own reasons of course, and Green Arrow could decide to help or not. But either way, awesome fight scenes commence!
She could be DC's answer to Daughters of the Dragon. She wouldn't even need a codename. She could just be "Cain." It's snappy. And could totally be used for Kung-Fu/Kung-Fu the Legend Continues type homages.
Cass Cain as your wandering martial artist do-gooder, a mix of Jonah Hex and Richard Dragon. I would fucking love that. Hell, I think it's infinitely better suited to getting her on TV than the Batgirl gig. An A-Team (with wacky supporting cast!) or Kung Fu: The Legend Continues style setup where the drifting hero rolls into town, finds the trouble, beats the crap out of it and then moves on.
Thing is, in order for it to work, DC would have to fucking commit to taking her BEYOND the Batbooks. They'd have to launch it out of a guest shot in something like Green Arrow, let it go at least a year before she hits Gotham again (but they totally need flashbacks to Oracle's tutelage as well as her relationships with Bruce and her parents) have her guest star in high profile books like Superman, Wonder Woman and Green Lantern, and make her prominent in your crossovers. Make her a DC UNIVERSE character, not just a Batcharacter.
And after she's built herself a brand, a supporting cast and has an identity that's not dependent on being a Bat, that's not a supprtimg cast member, that's got ties beyond Gotham... Then you can have her buddy-cop team up with Steph-Batgirl because she won't have her place in the DCU dependent on the musical identities played by the Batfamily anymore.
I certainly don't trust DC to do this right at this point, but if they are married to Steph-Batgirl then Cass would have a better chance this way than as the back-up Batgirl. If they tried this angle, I'd read it. And if they put some effort into it and really tried to build in what they have rather than just letting her pop up as an ex-Batgirl now and then... I'd cheer it.
But she can't be Lady Shiva. That's her mom's name. Richard Dragon, Misty Knight and Colleen Wing all use their own names. Cassandra Cain is full of mystery and symbolism, it's perfect for this sort of character, and in this case a play off of Kathy Kane becomes a reference to Kwai Chang Caine.