I know that sounds like a strange question. Let me start by saying that I think I have a pretty good understanding of Petrine primacy/papal supremacy, and as a Catholic, I’m fully on board with the pope being head of the Church. However, I was recently confronted with a few hypothetical questions that I was unable to answer.
Based on my understanding, while the pope in some ways is a bishop just like any other bishop, he is special (I know that’s probably not the best word), because, as bishop of Rome, he is the successor of St. Peter, who founded the episcopal see at Rome and was its first bishop. However, St. Peter is also considered to be the founder and the first bishop (or patriarch) of the patriarchate of Antioch. So couldn’t the bishop/patriarch of Antioch also claim to be the successor of St. Peter?
I reasoned that the bishop of Rome outranked the bishop of Antioch due to Rome’s historical significance and the fact that Peter and Paul were both martyred there. However, what if somehow in the future Rome no longer exists? I know this is really far-fetched, but bear with me. What would happen if say the whole Italian peninsula was totally wiped out by a nuclear attack or natural disaster? Who would be the pope then, and what would be the rationale behind his authority?