I'm pretty sure Incubus isn't dead. Maya's plot revolves around him; for him to be killed off without them getting to interact again feels wrong. If he is dead, she will at least encounter his corpse.

I do hope Jadis isn't dead — we haven't seen her do anything, and I'd really like her to be more involved than delivering a prophecy way back near the start of the comic.

Mottom and Mammon I could see being dead. They're both relatively weak among the demiurges, and I don't see as many unresolved plot threads with them. Solomon David is a lot stronger, but honestly, I mostly think we're just waiting for him to do a ten-point ki rata strike.