Can a Community Fork Be Considered a Last-Resort Defense against a Successful 51% Attack?

Yes, a community-led hard fork can be a powerful last-resort defense. If an attacker successfully executes a damaging 51% attack, the community of users, developers, and miners can agree to collectively ignore the attacker's chain.

They can release new software that contains rules to invalidate the blocks created by the attacker and essentially 'fork off' to a new, clean version of the blockchain from a point before the attack began. This socially-coordinated defense effectively erases the attack but requires strong community consensus and can be a messy, contentious process that risks splitting the network permanently.