For true AGI (whatever that means, lets say fully replicates human abilities), discussing "developers" only is a drop in the bucket compared to all knowledge work jobs which will be displaced.
The new capabilities of LLMs, and generally large foundation models, expands the range of what a computer program can do. Naturally, we will need to build all of those things with code. Which will be done by a combo of people with product ideas, engineers, and LLMs. There will be then specialization and competition on each new use-case. eg., who builds the best AI doctor etc.,.
The pundits response to the (alleged) plateau was proportional to the certainty with which CEOs of frontier labs discussed pre-training scaling. The o3 result is from scaling test time compute, which represents a meaningful change in how you would build out compute for scaling (single supercluster --> presence in regions close to users). Thus it is important to discuss.