The reality is that probably 99.9999% of code bases on this earth (but this might drop soon, who knows) pre-date LLMs and organizing them in a way that coding agents can produce consistent results from sprint to sprint, will need a big plumbing work from all dev teams. And that will include refactoring, documentation improvements, building consensus on architectures and of course reshaping the testing landscape. So SWE's will have a lot of dirty work to do before we reach the aforementioned "scale".
However, a lot of platforms are being built from ground-up today in a post-CC (claude code) era . And they should be ready to hit that scale today.