STDG
Yes but we've had that bit IYSWIM
At the end of the novel she leaves in a van at Nicks instruction - she doesn't know and the reader never knows if she is going to her freedom or her execution. So we can't look to the end of the book for clues because that's played out now.
The final, final bit of the novel is the idea that the book we've just read was a taped interview with June now being discussed by scholars in another country, a very long time later.
What I mean is, if they wanted to go with the book they'd have had to make it one series only, so don't bet any future plot on how the book ends