It's possible, but I don't see any reason to assume that it's more likely that machines will be able to code as well as working programmers yet not be able to come up with requirements or even ideas as well as working PMs. In fact, why not the opposite? I think that currently LLMs are better at writing general prose, offering advice etc.., than they are at writing code. They are better at knowing what people generally want than they are at solving complex logic puzzle that require many deduction steps. Once we're reduced to imagining what AI can and cannot do, we can imagine pretty much any capability or restriction we like. We can imagine something is possible, and we can just as well choose to imagine it's not possible. We're now in the realm of, literally, science fiction.