Stranger things have happened... But I think the evidence favors the conclusion that Graendal is dead.

Plus, I want her to be dead because that scene made Dark Halo Rand worth it. That was simply awesome. That is the kind of thing Rand should have been willing to do to a forsaken without being stark raving mad. The build-up was awesome. You could tell crazy evil Rand was about to do something RJ would never let crazy good Rand do.

IMO, this scene was one of the best in the series. If Graendal survived it, then its awesomeness is reduced to almost nothing... although Graendal herself would be quite a bit more awesome.