Most ladies I know into wargaming like tyranids and necrons on the 40k side, and lovecraftian abominations on the other.
I expect Sisters will be the next "dark eldar", in that they will have a load of new plastic stuff that looks utterly awesome and they will be at least somewhat popular for it. The Ecclesiarchy seems like it would be a pretty definitive army for 40k with all that gothic space church stuff too.