The Gantt shown is an example of Waterfall, or some other method where there's a final destination for the software. 99.999% of software today is not made that way.

In modern software development, there is no destination. On a 2-week basis, the business decides to change what the software is supposed to do. New features. New integrations. Changed features. Upgraded/replaced components. Larger scale. Different hosting.

Over years, the software is fundamentally altered. Quality and testing goes out the window. There's a constant slog, not only of trying to deal with modifications in an ad-hoc way, but also in fighting entropy. The software becomes a living being, which gets injured, changes its lifestyle, ages. The company is a custodian of a monster, like a zoo keeper, trying to keep the depressed animal alive.

Since humans are creatures of habit, all the same problems will happen with AI. But everything will be a little bit faster, and code reviews will make code a little bit better. But simultaneously, a lack of good tests and the desire for faster deployment will make everything a little bit worse. This push and pull will result in about the same level of software quality, but moving slightly faster. So in the end we will have a faster process. But nobody will really notice, because the rest remains a slog. We will all probably get burnt out faster.

It's complex for a reason, and you can't remove the complexity without removing the reasons. You can't solve business problems with tools.