What happens to my wallet if Sequence were to stop operating?

Sequence is non-custodial, which means we don't hold the crypto, so us going away doesn't affect your wallet. All you would lose is a user interface. There might be some extra work required for you to be able to execute your transactions but all steps for you to take, or if there is a need to do a few lines of commands, it will be documented in a public repository and accessible by following simple instructions. since its open source, or, ideally, by running a single command.