I don't know where you have been for over the past 5 years, but not only did some of those not disappear, they had a massive resurgence (in the US/Canada, at least).
"Emo rap" has been all the hotness over the past 5 years, just look at artists like Lil Uzi Vert or Frank Ocean. Skrillex, one of the most successful producers and artists of our time, went back to his original emo rock band and recorded a single with them to a wide applause. Goth-related discussions have seen continuous increase in numbers on social media.
>Most of the people who would have fallen in one of the aforementioned groups a decade ago are now non-binary, gender fluid, etc.
I don't see how those things are mutually exclusive. Plenty of non-binary/genderfluid/etc. people would count themselves as a part of those groups, just like cis/straight people would.
I will give it to you with scene and hipsters disappearing, but "hipster" as a term has been used almost always with negative connotations (as others in this thread have pointed out already the specifics of why people scoffed at "hipsters" as used the term as an insult). Even at the peak of popularity of that term, I don't recall almost anyone using it to refer to themselves, though this point is entirely subjective and anecdotal on my end.
The point you were trying to make would have been indeed interesting to look into, if the reality matched a bit closer with what you were claiming was happening to those emo/goth/etc. groups.