Was just testing latest gen LLM capabilities, and decided to give it goal of rewriting a small opensource project in Rust. (Should be noted: was not some tiny library, but an actually useful network service).
It completed the entire rewrite from typescript to rust in about 2 hours, ~600k tokens used. Worked perfectly on first try with no follow up changes required. Memory and CPU usage now a tiny fraction of TS version (obviously). Rust code was simple, easy to read, accurate test suite, etc.
I was pleasantly surprised.
Obviously bigger code bases with more complex business logic will likely struggle here, but there are some advantages to "RIIR" when performance matters, even security benefits aside. Rust can help squeeze more juice out of old hardware; reduced memory footprint especially helpful with current RAM prices.
For small services where operational cost matters, having LLMs "rewrite it in rust" might be worth the spend.