Aran'gar not dying, that I can see going either way. As a character, she/he just doesn't have enough personality for his death to have any thematic closure. So it could have gone either way.

With Graendal, though, I don't think being made a Myrdraal's sex slave is the best end for her. Chiefly because RJ made it clear that the naked playthings and the hedonism was all a screen. Sure, Graendal liked her pleasures, but she wasn't a slave to them, she didn't absolutely depend on them, which sets her apart from Semirhage.

The true core of Graendal's personality is a lust for control. It is Graendal who wants "a place for all things and all things in their place", with the decisions on who belongs where, and who gets to do what being totally under her control.

She perverts beauty and sexual pleasures by taking them to their extreme, but she also perverts the idea of order. She was the second of the Foresaken. It is no wonder that it is Graendal's revelation of her affiliation to the Shadow that marked the start of the WoS. In many ways, she is the female representation of the Shadow.

The true end for her, I believe, will be loss of control, via a mindtrap. No longer able to scheme, the pawn-maker will be made the pawn. From the tGS prologue, it seems obvious that her repeated thoughts on making Moridin a pawn have been read by his Zomoran. I think her lack of control over herself will be rubbed in her face, and like Cyndane and Moghedien, she too will be made Moridin's pawn.