he keeps coming back to the prediction that Voltaire will die as a repentant son of the church with priests at his side out of fear, he's obsessed with it.

I have yet to read through the diary systematically to see these passages in context, but I'll just note that this is something Fritz obsessed about with other people, like La Mettrie. Whom he was relieved to find *didn't* break, contrary to rumor. Who's the other one I'm thinking of, Rottenburg? Anyway, it's something Fritz worries about. And I think Fritz talks a lot about how hypochondriacal Voltaire is, so I think he has an impression of Voltaire as someone afraid of death. I'm not certain, but that may be relevant.