Ultimately you'd have to decide which one you want to treat as the canonical chain. There would be two (or more) parallel histories, and users would have to fig

Ultimately you'd have to decide which one you want to treat as the canonical chain. There would be two (or more) parallel histories, and users would have to figure out which one they wanted to follow. By default, all users would go along with the original chain. To follow the chain with the updated rules (whatever rules the developers couldn't agree on), a user would have to manually opt-in to that updated set of rules.