Humans, you know, are also "trained" as they grow up. And the new generations, growing up much more exposed to the AI-generated media from the earliest ages, may as well end up finding AI porn just as — if not more — sexy as human-produced porn. That too is a speculation, yes, but considering the whole history of humanity full of vast shifts in cultural and aesthetic norms, it's a very mild speculation.
While I hesitate to use it in this context, reminds of one of Planck's principle - "progress, on funeral at a time"