Jacobs ultimately learns that all humanity (including his beloved wife and son, whose deaths triggered his obsession) is doomed to spend eternity after death enslaved to an Eldritch Abomination covered in human faces. Except this is a man who has always known that the most horrific thing that could happen to him is seeing the faceless body of his young son. He never needed to look into the Other Side. He's already seen it once.
That...or maybe Null/Mother was sending him a message.
King tends to link his stories in a Shared Universe, and a reference to Joyland is made in the novel. Unless there comes a character or group who can ensure Null/Mother is vanquished like It, everyone who dies in King stories set on the same plain of existence as Revival is royally screwed.
Unlikely, as several different afterlives have been shown throughout King's novels, ALL of them cant just have been Mother screwing with everyone.
Knowing what we know about the afterlife in Revival though, is it any wonder Gage and Church came back as messed up as they did in Pet Sematary?
Another possibility is that the burial grounds serve as a gateway to the Null, and the entity that takes over the bodies buried there is another of the creatures living there like Mother.
