Rather, all his prophetic statements should be taken as things the author wants us to believe are definitely going to come true. We have no knowledge of how the Oracle's prophetic gift actually works, except that the author allows him to say things about the future, and all the ones that have been resolved so far have come true. We don't know whether this one will come true or not until it actually happens.

Sure, you can say: "If it's not going to come true, why did the author introduce the prophecy into the story?" But there could be other reasons. The Oracle (or his divine source) could be lying or mistaken, and either way there could be an interesting reason for it that we don't know yet. This is an author with a long track record of surprising us and making the most unexpected twists actually work.

Sure, I think it's most likely the prophecy will simply come true. I just wanted to point out that "the Oracle said so" is not a sufficient reason for claiming absolute certainty.