Quite a lot of SEO already uses simple word generation techniques. It isn't clear GPT-3 is an improvement there - human text recognition might not be whatever Google does.
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.