The main strong points for dark aelves/ shadowkin in old WHFB were the witches, the crossbows, executioners and later on the scourge privateers had a seemingly separate but still thematically strong place. I wouldn't be surprised to the daughters of khaine get the initial bulk release with someone like Morathi and some redone models for darkling covens. I also wouldn't be surprised to see order serpentis lumped into another subfaction like scourge privateers.