There are many different important issues raised by this thread. The comparison to furries is instructive and probably deserves its own thread.
I was about to ask @TakoAlice8 what she imagined size fantasy “going beyond the fetish” would look like, but her recent post clarified that somewhat. “Fandom” was precisely the word I was going to suggest, primarily because it captures that obsessive interest that defies mainstream acceptance. I agree with @AnnDViant that “going mainstream” would almost certainly transform size fantasy, quite possibly losing what fans (both SFW and NSFW) love about it.
Like many long-time size fantasists, I have often lamented that whenever size differential appears in mainstream content it fails to address my personal, fetish-based interests. If size fantasy were to “go mainstream,” I argued, there would be many more opportunities for them to “get it right.” Judging from the SFW G/t folks still on Tumblr, mainstream size content also fails to deliver on the important tropes of what they call their “emotional support fantasy.”
At present, mainstream size content is restricted to children’s stories and fantasy/sci-fi/horror. The “holy grail” would be a size story that is, as Ann put it, more adult and less paranormal. This would create the dramatic space for encounters that satisfy the needs of both SFW and NSFW size fans. For a while some of us entertained the hope that the movie Downsizing would be that breakthrough moment, but we were disappointed (to put it mildly).
I’m no longer waiting on the mainstream media to catch on to this. I’m trying to write more stories that are dramatically adult that just happen to include size differential, with relatable people of different sizes who have complex relationships. I still write the short stroke stories when necessary, of course.