From the 31st of May till June 1st Optimism had around 11,000 to at its peak 14,000 transactions per hour. Currently the network has an hourly tx traffic of around 2,000.
This is a significant decrease of network use. Optimism greatest strength is that it uses Ethereum for transaction fees. The Optimism Network could incentivize node operators, governance participants, and token holders with these Ethereum fees for contributing to the network.
There could also be a treasury developed to accumulate funds in a war chest in order to progress Optimism adoption by Ethereum developers.
The distribution of tx fees will incentivize the use of Optimism by providing people that upkeep the system or interact with the system rewards for their contributions.
The airdrop demonstrated that more people used the network when there was an incentive to do so. The future airdrops are good but if Optimism has a consistent incentive structure in place then the hourly transaction rate will clock in at a higher rate.