Conversion of legacy nontrivial C++ code bases into Rust (or anything else for that matter) feels like it should be one of the "Millenium problems" for AGI. That and full self driving - including the nuances of gesturing to a human about who's going to reverse in a single lane in a snowstorm.

But if 50% of code can be converted automatically to safe idiomatic Rust? Great. Doesn't sound too far fetched. But yes, there's certainly a long tail here.