While this is a great argument that there will be more software in the future (something that I don't think anyone disputes), it's not an argument in favor of the proposition that there will be more developers, because the whole point of AI-driven development is to automate what a developer does.
One reason there are a lot of businesses still using antiquated systems is that 1) the systems work for their purposes, so their need is not acute; and 2) custom software development is expensive. Your local gym can't afford to pay someone thousands of dollars for a custom app (or even hundreds of dollars for a customized version of an existing app). But AI-driven development promises an order of magnitude drop in cost. So yes, we should see a lot more digitization as it becomes available.
I do agree in the short term that it won't drive the number of developers down, since for the foreseeable future skilled people will be needed to oversee the AI product. But it will vastly increase productivity. Unfortunately, if history is any guide developers will not reap any of the rewards for the increased productivity, and their real wages may actually decline.