At the moment, good code structure for humans is good code structure for AIs and bad code structure for humans is still bad code structure for AIs too. At least to a first approximation.
I qualify that because hey, someone comes back and reads this 5 years later, I have no idea what you will be facing then. But at the moment this is still true.
The problem is, people see the AIs coding, I dunno, what, a 100 times faster minimum in terms of churning out lines? And it just blows out their mental estimation models and they substitute an "infinity" for the capability of the models, either today or in the future. But they are not infinitely capable. They are finitely capable. As such they will still face many of the same challenges humans do... no matter how good they get in the future. Getting better will move the threshold but it can never remove it.
There is no model coming that will be able to consume an arbitrarily large amount of code goop and integrate with it instantly. That's not a limitation of Artificial Intelligences, that's a limitation of finite intelligences. A model that makes what we humans would call subjectively better code is going to produce a code base that can do more and go farther than a model that just hyper-focuses on the short-term and slops something out that works today. That's a continuum, not a binary, so there will always be room for a better model that makes better code. We will never overwhelm bad code with infinite intelligence because we can't have the latter.
Today, in 2026, providing the guidance for better code is a human role. I'm not promising it will be forever, but it is today. If you're not doing that, you will pay the price of a bad code base. I say that without emotion, just as "tech debt" is not always necessarily bad. It's just a tradeoff you need to decide about, but I guarantee a lot of people are making poor ones today without realizing it, and will be paying for it for years to come no matter how good the future AIs may be. (If the rumors and guesses are true that Windows is nearly in collapse from AI code... how much larger an object lesson do you need? If that is their problem they're probably in even bigger trouble than they realize.)
I also don't guarantee that "good code for humans" and "good code for AIs" will remain as aligned as they are now, though it is my opinion we ought to strive for that to be the case. It hasn't been talked about as much lately, but it's still good for us to be able to figure out why a system did what it did and even if it costs us some percentage of efficiency, having the AIs write human-legible code into the indefinite future is probably still a valuable thing to do so we can examine things if necessary. (Personally I suspect that while there will be some efficiency gain for letting the AIs make their own programming languages that I doubt it'll ever be more than some more-or-less fixed percentage gain rather than some step-change in capability that we're missing out on... and if it is, maybe we should miss out on that step-change. As the moltbots prove that whatever fiction we may have told ourselves about keeping AIs in boxes is total garbage in a world where people will proactively let AIs out of the box for entertainment purposes.)