Just a guess but: I suspect a bit that foot thing might be to lower fractions of NSFW parts in an image for otherwise SFW websites(e.g. Twitter), and also to appease older demographic because it is often argued that fetish move downwards as people ages. "Step sibling" is just a successor to "teen" and "schoolgirl" for ban avoidance. There are chances that a successor will appear in 3-5 years and my instinct says it could be a nationality tag.

> because convergence is essentially the goal of data driven production in the first place.

But what comes after an ultimate convergence - let's say, a 3:45 minutes long .mp4 file of an incomprehensible psychedelic rainbow mosaic that cause a strong euphoria to any singular entity of a primate species born in or before 2022 - will audiences not adapt to it? And when they consume the stimuli, how does the convergence sustain? There will have to be a change of trend, and a novel oddity to be normalized will have to be brought in from outside the industry, I think.