The Bringer of Chaos was once a servant and caregiver to the gods, long ago. She cared for both the Fanged God, whom we often channel in some of our coven rituals, and the Winged Goddess, whom we often curse and spite. However, she became greedy and hungry, wanting to be equal to them and immortal. She conducted acts that the gods denied her and told her not to do. This enraged the gods. The Bringer became a horror and demon that even us Sith witches would not dare wish to face.
But the prophecy states that one day, lost members of the Sith, and the Jedi alike, will be threatened by the Bringer. When the Bringer escapes her prison, the galaxy will be brought unto chaos. Who are these lost Sith? Are they lost already or will they be lost later? Are they physically lost or will they lose their way by becoming light? We do not know. Perhaps the gods do not know or do not want us to know. Will the chaos consume all or will the people of the galaxy survive?
In recent years, Jedi and Sith have shown to maintain the ability to work together when mutually threatened by the likes of Revan and the Eternal Empire. Perhaps, whenever the prophecy comes to be, we will see such a temporary alliance again.