Quantitative measures of this are very poor, and even those are mixed.

My subjective assessment is that agents like Copilot got better because of better harnesses and fine tuning of models to use those harnesses. But they are not improving in the direction of labor substitution, but rather in the direction of significant, but not earth-shaking, complementarity. That complementarity is stronger for more experienced developers.

Agree. Nice to see a post with proper economic thought on the topic.