AI Economics (of money, anyway) aren't what'll kill writing. The vast, vast majority of writing is already not done for money. Approximately nobody makes meaningful amounts of money writing.

The existence of a sea of AI slop making it impossible to find or publicize writing is what will kill it.

It's purely a loss.

Great point. Reminds me of the misinformation wars. People who respect evidence-based knowledge need to defend against a never ending onslaught of conspiracy theories. They only need to slip up once, while the other side of doubt can run their engine forever with the latest flavor.