Seems pretty un loseable to me as well

When statistics to extract keyphrases from messages encoded with Vigenere ciphers became public, nobody "lost" the knowledge of Vigenere ciphers, its the Vigenere cipher losing utility.

There is a social aspect to cryptography: the study of what types of puzzles we don't publicly know how to solve (yet) can in some cases be used to construct cryptographic primitives, so that we can derive cryptographic value (access to cryptography) from parts of mathematics we don't understand yet, this obviously relies on the main body of mathematics being publicly accessible.

That window on mathematics (the puzzle needs to be employable as a cryptographic primitive AND the puzzle needs to hard enough) is expected to vary over time, as long-time puzzle types fall, and hopefully new puzzle types emerge.

One observes no guarantees on the window width, nor on how fast that window is sweeping over the frontier of mathematics (even if humans aided with LLMs are continuously capable of finding fresh cryptography, useful for a while until it expires, it takes times to manufacture hardware to replenish all end-user electronics, so if the cadence is high enough, we might continuously have novel forms of cryptography, in time as formula's, but too late to secure the boot chains across humanity, surveillance states may encounter periodic black-outs if people jailbreak their phones with the latest LLM knowledge).

Politicians will try desperate things like criminalizing mathematics...