1 - Slightly reduce current real-time epoch rewards and redirect to a programmed contract/vault to be released to the staker after a certain amount of staking time (ex: 30, 90, 365 days/epochs). To prevent large dumps at the end of each term, have a daily/epoch limit on number of stakers admitted to the contract (10, 20, etc.) or amount of OHM per day and a reservation system. I think this would encourage more staking/retention. Early Unstaking would forego these rewards and redistribute to those still standing or returned to the DAO.
2 - Another option would be having a time-locked rewards pool of NFTs, donated by the community, an artist trying to make a name and/or purchased by the DAO. I think with the current NFT craze this would bring Olympus to the attention of a large amount of potential members.
3 - A mix of 1 and 2.