User blog comment:Hyperborean/"The House of Hades" – official expectations blog/@comment-24205801-20121113042059/@comment-74.134.155.110-20121113045903

I'm pretty sure that these gods breathe, but you make a valid point. It doesn't necessarily mean that someone will die. And it's also a possibility that someone may be turned into a god - most mortals-turned-gods in mythology had died before being resurrected as gods.

I think I said it somewhere else, but it's also possible that the oath might not have been mentioned yet, or will even be completed by the next book. As far as I recall, this is still planned as a five-book series. I would find it strange if the entire prophecy is finished before we reach the last book.