Doesn't that mean these 33k tokens can be cached, since they don't depend on the input? The model can just start generation on the 33k+1th token.
Anthropic even changed this silently: https://www.reddit.com/r/ClaudeAI/comments/1sk3m12/followup_...
Although saying that out loud makes me question it - each per-user chat and growing cache would need eventually to own its own ~contiguous memory block.
I think that Anthropic will bill you in any case :D