My Theory **SPOILERS**
I think Misty dies at the end. Anyone remember the diary Misty stole from Grace? It was either Maura’s or Constance’s diary. I forget who was last. This diary ended before the hotel fire of her generation. Misty had no idea she was being led to her death by Tabbi. While Misty was locked in the room with the skeletons of Maura and Constance she consciously finishes the diary explaining her final days. When history repeats itself and the 4th generation woman Nora Adams steals the diary from her husbands mother (Misty’s Diary) she knows exactly what will happen. And Nora Adams sends Misty’s diary to Chuck while off the island before the fire and/or her demise. Maybe Nora visited where Misty lived to find out more about her and sent the diary from there. Or maybe she just used it to make her anonymous. I also think that by each generation stealing the previous generations diary was the demise of the ritual, each generation getting smarter and more informed about the plan.