Quote dwja: Seeing KMc chose to leave I think it makes sense to kill the character off. Her and Patrick are happy and they have a child. What other way can she leave without either ripping the couple apart after they just reunited or making either Robin or Patrick look really bad in some way. It can always be done in a way that leaves some sort of mystery so she can return if she wants.
There's always the coma route. Put her in a deep sleep until the finale of GH and bring back Stone. Let them have some nice long scenes in which he finally tells her to go into the light but instead of the light meaning death, it means she finally wakes up with Patrick, Emma, Mac, Anna, and Robert(the last 2 are a pipe dream) standing by her bedside.