We've switched from authors (novels and non-fiction books) to writers here. That's a very different question.

Sure if you include writers writing for business, translators etc who were never very valued by business, there has been a huge impact already, because business is willing to accept shoddy results if they are good enough and put up with mistakes and poor style. That low end of generating content has definitely been impacted, for example in social media as I mentioned LLMs have replaced a lot of 'writers' who generated filler text for content advertising.