Fads come and go in industry. This version of LLMs will come and go as well, as will the coding languages and paradigms we used before (and, presuming you want your code to actually run, still do with some decent frequency).

Will LLMs in their current ergonomics have staying power? Perhaps. Nobody can predict the future. But I don’t think it’s a given in the least

Automatic coding systems have way too much economic value to be considered a "fad". I don't think you need to be Nostradamus to predict that we're never going back to manual coding. Sure, the systems will evolve and improve, but they're certainly not going anywhere.