I think it's difficult to say agentic and human developer labor are fungible in the real world at this point. Agents may succeed in discrete tasks, like those in a benchmark assessment, but those requiring a larger context window (i.e. working in brownfield systems, which is arguably the bulk of development work) favor developers for now. Not to mention that at this point a lot of necessary context is not encoded in an enterprise system, but lives in people's heads.

I'd also flip your framing on its head. One of the advantages of human labor over agents is accountability. Someone needs to own the work at the end of the day, and the incentive alignment is stronger for humans given that there is a real cost to being fired.