Two years ago, they got rid the calling part of that. Girls who have the potential to be Slayers just become them without having to wait for the previous one to die off first.

[ he... doesn't necessarily approve of what they did. brilliant war strategy, yes, but unfair to all the girls who while in possession of the potential, where never meant to be slayers. girls like dana. deranged and broken beyond repair, gifted with a power that she shouldn't have. ]