I predict Kylo Ren will cut Rey’s head off.
I predict that he then undergoes a medical procedure to attach her head next to his own, and this two headed monster proceeds to rule the galaxy as Emperor Reylo.
Just what we need, a The Thing with Two Heads rehash.
It is inevitable at this point. Remember Maz’s line from TFA: “The belonging you seek is not behind you, it is a head.”