Writers and liberals arts are under the automation threat for the first time ever.
Sure, companies might be able to have ChatGPT and its brethren spit out marketing copy and similar types of writing that are, to a large extent, about chasing the lowest common denominator. But even if we grant for the sake of argument that it's possible to train an LLM that can create, say, a brand-new "Shakespeare" play, without enough input and tweaking that it will take a writer or a liberal arts major to do it anyway, that day is a long, long way off.
No; the only people I've heard talking about how all the knowledge jobs will be automated away by ChatGPT (or, more commonly, just all the "unproductive" humanities-type jobs—because, of course, the humanities are something we can totally hand over to LLMs with no negative consequences) are more tech-oriented people with vastly inflated ideas of ChatGPT's abilities and the tech sector's primacy in the world. The humanities people I've talked to about the subject tend to fall either into the "this is a bunch of BS hype" camp or the "I've watched too many sci-fi movies and think Skynet is launching tomorrow" camp.
We don't have AGI yet, so no Skynet isn't here, but that doesn't mean we shouldn't watch out and make sure it doesn't show up and that we have a regulatory framework to ensure Skynet doesn't happen.
And, no liberal arts majors are not going to be replaced, but that doesn't mean they are coming out unscathed either. Things like GPT are going to force further specialization as we offload the generalized work off to tools like this. Now, humanity has been doing this for a long time so this is nothing new, but specialization is risky, even a small change in technological capability and the thing you trained your entire life for has been replaced by a small shell script and you're left trying to figure out how to pay rent next month.
The author of the biggest comic in the world "one piece" admitted to using gpt to write and plan future storylines.