I literally learned prompt engineering from you for the first time two days ago (thank you btw! it was great!)
But didn't you mention that there may be some ways to isolate the user input, using spacing and asterisks and such?
I agree though that leaking a prompt or two by itself doesn't really matter. What's probably a bigger concern is security/DoS type attacks, especially if we build more complicated systems with context/memory.
Maybe Scale will also hire the world's first "prompt security engineer."