I think what you discribed is already happening on Douyin (the China version), on which the initial novelty had long worn off, people no longer just/or largely post for fun.

It's all about monetization now, any view is meant to generate profit, every poster is peddling something, like the Instagram accounts you described, there are endless regurgitating of news events, movie and TV show digests.

There are content factories searching for beautiful faces to appear in their merchandise tiktoks, but only the face part (kind of a remote job?), not the voice and acutal body, those will be produced in their assemly lines and match with your face.

Maybe western users are accustomed to higher standard videos, but the late stage will inevitably come. And the lower the entry barrier, the uglier the scene will become.