If optimism were to go down, would Farcaster also go down?

I understand OP chain is used to associate FIDs with Ethereum addresses - I assume this would fail if OP had a liveness issue?

"Go down" as in permanently deleted, or just a temporary downtime? If hubs do not have access to OP, they will not be able to parse onchain tx, such as account creation, signers approvals, storage units purchases. But the content would still be live, and existing users would be able to interact.

Dad, geek, conversation liquidity provider. vrypan.net (home), @l--o--l (fun).

Downtime.

And what portions would be down. I think your answer helps (eg no new user registration) … sounds like partially degraded service

An easy rule of thumb is if OP is not available, you won't be able to do all the things that prompt you to pay something.