To quote zviad from discord:
CELO distribution curve is quite long. That is at least 20-30+ years out in the future. Most likely even within 10 years, bunch of things will change wrt to validator payments.
There are many ways validators can get paid without CELO inflation:
→ They can get paid from the reserve. assuming network is successful, reserve will be expansionary so it will have funds to spend.
→ They can get paid by directly extracting MEV from the network. Once/if network gets more traffic, there can be more ways to extract fees from transactions other than just direct gas fees. For example: Priority transaction ordering and placement can have a cost which can fund all the validators. (If you are familiar with flashbots on Ethereum, that would be something similar).
→ There are also many otherwise that can show up in the future. Once network is actually doing useful amount of work, it will be fairly easy to find a way to extract fees to pay to the validators to secure the network. And it is more likely that validator pay will increase in future as network gets larger and starts securing more overall total capital.
and also Tim:
Also - Validators and Validator Group rewards are made in cUSD, so if the price of CELO goes up, the CELO set aside for that purpose lasts longer. The bigger question (and bigger budget) is rewards for voters who lock their CELO – over time, this may be addressed by a proof of stake system that can scale to more validators and is less dependent on offering high yield for locking up funds.