In theory - if an LLM could handle infinite complexity, I still think that the business issues + decisions end up getting in the way somewhere.
AI: "You asked to add feature X. Here are 25 questions that impact feature Z, B, and C in your gigantic codebase"
Developer: I can answer 8 of these questions... Guess I need to go figure out the rest of them.
Writing the code + building the functionality has always been the easy part.