LLM's need to be trained on something, and the more the 'market' for text is flooded with ChatGPT output, the more relatively scarce human-written text will be. However, if in the long-term, LLM's hinder peoples' ability to string together sentences or otherwise affect the quality of their writing, then (modern) human-written text might not be so valuable. In this case, the value of past human-written text will skyrocket (Twitter, Reddit, etc. will make a killing).