This tech can easily be used to flood humanity’s shared brain with auto-generated propaganda. Schizophrenia of the internet in a way. There is plenty of incentive with Google algorithms favoring number of words and relevant keywords in content for rankings - you could have NLP bots lifting junk sites to top results.
To step ahead in that chess game, a detection tool for fake would be just training grounds for better GAN. Instead we may see a certifying authority that labels content as human generated, certified fact maybe? Wikipedia and reddit are not safe without fast automatic moderation either.
Do you have a brainstorm or idea/prototype submission site where people can submit approaches to countering bad ai actors? An white/grey hat ai bounty program of sorts?