Apparently she's goingto play a "prominent" role in Batgirl next year.
Whether this means she'll be a supporting character who mentors Steph or something, or she does a Mary Marvel and goes evil again we'll have to see.
Apparently the reason she quit was that she was heartbroken that just after getting over her issues with her biological dad and getting a "real" one in Bruce, he was taken away from her.
Maybe she quit to wander to Prada Nambat or whatever it's called to get her head together before becoming a new sueprhero or something.