Will that happen in 1,2,5,10 or never years?
I mean if AI output exceeds human quality then all humans will be redundant. So it would then be quite a brave new world!
My point is that I do not agree that LMM output will degrade all media (as there is always a demand for top quality content). So we either have bad LLM output and then people who care about quality avoiding such works. Or good LLM output and hopefully some form of post scarcity society (e.g., Iain Bank's Culture Novels).
Until LLMs exceed the very best of human quality there will be human content in all forms of media. This claims follows because there is always (some) demand for top quality content.
I agree that many writers might use LLMs as a tool, but good writers who care about quality will ensure that such use is not detrimental (e.g., using the LLM to identify errors rather than having it draft copy).