However, if the output needs to be curated and edited by humans, the scale and automation is gone - we just get a different manual process, with a modest improvement to speed at cost of some decline in quality, and that's not very impactful.
Google at this point favours long form content for many search intents. Being able to generate thousands of these pages in one-click is a real problem. Not just because of popular topics e.g. "covid-19 symptoms" but more so for the long tail e.g. "should I drink coffee to cure covid-19".
It may be that Google's algorithms don't care at all how human-like the text is, or that their own recognition algorithm/NN (whatever they use) isn't fooled. Even if it is affected, Google has the money and corpus to build its own competing NN to recognize GPT-3 text.
That said, there might be a different threat to Google. GPT-3 seems really useful as a search engine of sorts (with the first answer implementing the 'I'm Feeling Lucky' button). Tune it for a query syntax, and for getting the 'top X' results somehow, then we just need the web corpus and a basic filter over the results. We could have a very interesting Google competitor.