I really don't see the point of letting Graendal survive this. It's clear that RJ wanted to conclude most plotlines. Then he obviously came up with the cool idea that Rand won't play Graendal's game, but outsmart her by instantly using brute force. Why should RJ use a cheap twist then by letting Graendal escape somehow, so that his hero Rand actually looks stupid, if before RJ always indicated and showed that the Forsaken actually aren't that clever (especially if that means that one still has to deal with Graendal and has to come up with an even more brilliant plan to kill her).

Therefore her survival simply doesn't make sense. BS's statement that we will hear of Graendal in ToM and know at the end of the book, if she is dead, indicates as well that she is gone.

Furthermore, it's most unlikely that Graendal will have a PoV from before her death in ToM. RJ never jumbed back in the timeline to give a PoV of a person who already died. BS said he just wants to bring Perrin's, Mat's and the other plotlines up to date; nothing indicates that he will go back in Rand's plotline to confuse the readers even more. If anything more is revealed about Graendal's plans, we will learn it from the other Forsaken.