You can already see how good it is at coding. It does lack understanding context and memory and longer term planning. But honestly that stuff should be here by GPT-5 it seems relatively easier than other problems they have solved. So I wouldn't be suprised if it's already self improving by then.

Consider this -- an OpenAI software engineer probably already used chatbot to improve code, even if just a line. It means its already self improving just a bit slow, but with increasing speed no doubt.