Here they say that Cass will, a) Cass will be in Gotham Streets (so she'll be written by Paul Dini, Yay!) b) Cass will not die and pretty much also c) she will not be in the Batgirl title.
Dini will also be writing the Harley, Selina and Ivy team-up book, 'Gotham Sirens', which I'm also pleased about.