The rule is to follow the strongest chain, i.e., the chain that contains the most work is considered the one the entire network should follow (the chain of truth). If a new chain appears that differs in several of blocks (even up to 20/30; maybe 100), it is not that significant problem; the network will switch to that new, stronger chain. However, what would happen if an entirely new chain starting from the genesis block appeared with more computational power than the current one? According to the rules, we should follow the strongest (the new) chain, and all nodes that don’t do so would be considered invalid. But would the network really switch to this new chain? It is right to make the transition, but if it was done completely, everyone would lose their money in Bitcoin, people would lose confidence in the network, and it would completely collapse.
Therefore, in theory, and what is correct is to transition to the stronger chain, but would it really be done?
I’m not asking for predictions about the future or someone telling me what would happen in hypothetical scenarios, but I assume that people who have been involved in Bitcoin for over 5/10 years have thought about this, and discussions on this topic might have taken place in the Bitcoin community (conferences, forums, informal conversations, etc.). I expect there have been conclusions drawn from these discussions.
