With the scope of the experiment in mind, I think we can deduce from it that AI is just not able to produce good software unsupervised. It's an important lesson.
To make a wider point, let's look at another of your prediction: that in 2026 the quality of AI code output will be undeniable. I actually think we've already reached that point. Since those agents came around I've never encountered a case where the AI wasn't able to code what I instructed it to. But that's not the same thing as software engineering, and in fact, I have never been impressed by the AI solving real problems for me.
It simply sucks at high quality software architecture. And I don't think this is due to a lack of computing power but that, rather, only humans can figure out what makes sense for them. And this matters, because if the software doesn't make sense, beyond very simple things you can test manually, it becomes impossible to know whether it works as intended.
A Web engine is a great example, because despite the extensive shared suites of tests and specifications, implementing one remains a challenge. You can write code and pass 90% of some sub test suite, and then figure out that your architecture for that Web API is all wrong and you'll never get to the last 10% and in fact your code is fundamentally broken. Unleashing AI without supervision makes this problem worse I think. Solving it requires human judgement and creativity.