"Always" correct is a very high bar and likely unattainable. It seems much more likely that the amount of errors will trend downwards but never quite reach zero. How could it be otherwise? AIs are not magic god-machines, they have a limited set of information to work with just like the rest of us (though it might be larger than humans could handle) and sometimes the piece of information is just not known yet.

Let's say that in a few years the amount of correct code becomes 99% instead of ~80%. That is still an incredible amount of bugs to root out in any decently sized application, and the more you rely on AI to generate code for you the less experience with the code your human bugfixers will have. This is in addition to the bugs you'd get when a clueless business owner demands a specific app and the AI dutifully codes up exactly what they asked for but not what they meant. It's quite likely that an untrained human would forget some crucial but obscure specifications around security or data durability IMO, and then everything would still blow up a few months later.