What Is the Long-Term Implication of Relying Solely on Transaction Fees for Network Security?

The long-term implication of relying solely on transaction fees (after the block subsidy ends) is that the network's security budget becomes entirely dependent on the volume and value of transactions. If transaction fees are insufficient, miners will lack the incentive to secure the network, potentially leading to security degradation and increased risk of 51% attacks.

The network must maintain a robust fee market and sufficient transaction volume to ensure the economic cost of an attack remains prohibitively high.