While I have no idea how you would fit it in your current infrastructure, I certainly see a (BIG) use-case for: I have this 100 GB, store it somewhere safe (in glacier), I won't need it for the next year (unless my house burns down). I agree that is a bit different from ongoing daily backups with changes, but its also not THAT different from a customer perspective. That it doesn't fit with how you store blocks on the backend won't matter to a lot of customers.