"She shall return to you. Return to you she shall, and that shall destroy both of you, I fear"
That's one of the things the Soothsayer in Lemoyne can say to John in the epilogue. Who does 'she' refer to?
If it's Abigail, how would that "destroy" them both? Does it mean that she will suffer the long term of implications of John's revenge on Micah by being heartbroken and die in 1914? Maybe, but I'm not sold on it. Only thing is, the returning aspect would make sense in terms of her leaving John and later coming back to him when she knows he's changed.
Could 'she' mean Sadie? In terms of her visiting John to tell him about Micah? If so, would that mean that Sadie will die in the future because of her revenge, like John; will she be pursued by the government too? The credits don't suggest that the Bureau found anyone else but John, so again, not sure.
Or, could 'she' have a different meaning entirely that's not about a specific person?