When AI can reliably convert business-speak into efficient bug-free code, everyone will be out of a job, because the business owners will ask it to write them another AI to replace every other task their business does.

No, not remotely.

If people are truly novice, with zero programming experience, how would they know the code is correct? If not, how to debug it?

I would say this is more promising for scenarios to generate more formularitive things like business report generation. But even that, it requires in depth understanding of what those data/tables really means, and how to handle exceptions, etc.

Kind of. A theme in programming since the beginning has been automation. You're using a computer anyway to do a more or less well defined task, naturally programming itself is one of the prime targets for automation.

Programming languages are automation tools. Libraries. Frameworks. It should be pretty clear this is a lasting trend, and doesn't necessarily mean programmers will have more or less jobs (due to well known effects of automation such as enabling new applications and increasing demand from increased productivity). It does mean you probably need to keep learning to stay relevant, and use those tools to your advantage!

Not entirely, but might will lower the barrier to entry and make you require fewer developers.

Not yet, but I think our role will get more and more "meta"

not if we can get a head start on the market for artisanal code developers.