These questions presuppose that all the AI players will operate ethically. We already know that Medium material gets plagiarized, stolen and reposted. While theft is different from an AI scoop, it introduces yet another risk to writing online. It appears inescapable that all online writing can be used to feed some Terminatoresque machine learning algorithm designed to render human writers obsolete. Whether AI achieves this incrementally or in quantum leaps is secondary to the inevitable trend.
I would not consent to any AI use of my writing. Any further such intrusions would push me to only post the fluffiest nonsense on Medium or quit altogether.