Men pay for onlyfans not for the pictures. There's already unlimited free nudes of women online. Men pay for the delusion that a real woman cares about them. When the girl says "omg thank you so much. You're such a nice person. Stick around after my show so I can have a private 1on1" then the chick literally just asks a bit about the guy and the guy feels like this hot woman cares about him because he gave her some money.

AI can fake this. With advanced in ChatAI, we can essentially replace this aspect. The problem is that men think the real woman is being real. The men who buy into this stuff often don't believe it's fake. That's why when that Amroenth chick came out that she was married, her fans got furious because they felt cheated. A lot of guys truly felt that maybe they had a chance at dating her and that's why they gave her money, etc...

I don't think onlyfans will be replaced so quickly but I do think we're headed in the direction that it will be eventually.