Well they did say that Cass wouldn't be in the Batfamily anymore so that might not be the case... BUT Didio has occasionally lied in internets to throw people off.
So she might be Batgirl still, as well as appearing in 'the Streets of Gotham' OR she's taken on a Nightwingish role of not being directly affiliated with Bruce and Co. possibly getting a new superhero name and eventually venturing off on her own.
That or she suddenly goes "BLARGH! I BE EVIL NOW!" in the final issue of the Oracle mini, so Barbara pinches Cass' outfit and keeps it for herself/gives it to the next contender.