Yo, I had a random shower thought a few minutes ago.
Since Jack Manifold has no lives left, he’s technically a demon. He’s supposed to be dead, as he has no canon lives. But he’s not. It could be a case of Ghostbur, but he shows no symptoms of that. Or, it could be a case of Glatt. We know barely anything about Glatt, but we know HE remembers. Jack could be a demon. Therefore, if Niki were to die, he could most likely bring her back from hell or wherever, and they could continue killing Tommy. Just a thought.