I've seen Harry Potter Marriage Law fanfiction tropes die out because of ethics, expect trope-inversion, no-comfort, and darker stuff of course. Similar with Soulmate fanfiction. So shall reader desire for this. To speak frankly, this sub-culture and genre has a long way to go. Maybe 50 years.
Lol, expecting fictional indulgence of dark kinks to "die out because of ethics".
If the Marriage Law "died out" I suspect it was just a passing fad, or a victim of JKR's undermining of her own fandom.
Though as far as HP and love potions go, a rather sweet Harry/Luna fic did throw in an somewhat ethical use as background detail: granting that pureblood families did a bunch of arranged marriages for whatever reason, love potions could be used consensually to make the marriage stronger. "We want this marriage to work for alliance/economic reasons, and it will work better if we're in love, bottoms up!"