It's already happening [0].
Stackoverflow recently banned generated responses [1].
We're facing a new karma-generating strategy and, IMO, a policy is urgently needed.
[0]: https://news.ycombinator.com/threads?id=clay-dreidels
[1]: https://stackoverflow.com/help/gpt-policy
Edit: It's a bit hard to point to past explanations since the word "bots" appears in many contexts, but I did find these:
https://news.ycombinator.com/item?id=33911426 (Dec 2022)
https://news.ycombinator.com/item?id=32571890 (Aug 2022)
https://news.ycombinator.com/item?id=27558392 (June 2021)
https://news.ycombinator.com/item?id=26693590 (April 2021)
https://news.ycombinator.com/item?id=22744611 (April 2020)
https://news.ycombinator.com/item?id=22427782 (Feb 2020)
https://news.ycombinator.com/item?id=21774797 (Dec 2019)
https://news.ycombinator.com/item?id=19325914 (March 2019)
We've already banned a few accounts that appear to be spamming the threads with generated comments, and I'm happy to keep doing that, even though there's a margin of error.
The best solution, though, is to raise the community bar for what counts as a good comment. Whatever ChatGPT (or similar) can generate, humans need to do better. If we reach the point where the humans simply can't do better, well, then it won't matter*. But that's a ways off.
Therefore, let's all stop writing lazy and over-conventional comments, and make our posts so thoughtful that the question "is this ChatGPT?" never comes up.
* Edit: urgh, I didn't mean that! I just mean it will be a different problem at that point.