I think the tension between natural language and code is fundamentally about information compression. Code is maximally compressed intent — minimal redundancy, precise semantics. Prose is deliberately less compressed — redundant, contextual, forgiving — because human cognition benefits from that slack.

Literate programming asks you to maintain both compression levels in parallel, which has always been the problem: it's real work to keep a compressed and an uncompressed representation in sync, with no compiler to enforce consistency between them.

What's interesting about your observation is that LLMs are essentially compression/decompression engines. They're great at expanding code into prose (explaining) and condensing prose into code (implementing). The "fundamental extra labor" you describe — translating between these two levels — is exactly what they're best at.

So I agree with your conclusion: the economics have changed. The cost of maintaining both representations just dropped to near zero. Whether that makes literate programming practical at scale is still an open question, but the bottleneck was always cost, not value.