I think GPT-3 is very convincing for "soft" topics like the other HN thread "Feeling Unproductive?"[2], and philosophical questions like "What is intelligence?" where debaters can just toss word salad at each other.
It's less convincing for "hard" concrete science topics. E.g. Rust/Go articles of programming to improve performance.
An interesting question is what happens when the input to the future GPT-4 is inadvertently fed by lots of generated GPT-3 output. And in turn, GPT-5 is fed by GPT-4 (which already ingested GPT-3). A lot of the corpus feeding GPT-3 was web scraping and now that source is tainted for future GPT-x models.