So I don't know if this counts as a reference or cameo, but the next season of Precure entitled Kira Kira Precure A La Mode has two new characters that are blatant homages to Sailor Uranus and Sailor Neptune.
@Maria, Kira Kira Precure hasn't started airing yet so nothing's confirmed about them.
I doubt they'll ever explicitly state that the two are in a relationship as Precure targets a much younger audience than even the original Sailor Moon anime. But there's most likely gonna be some pretty obvious subtext between them. It's very clear that they're supposed to parallel Haruka and Michiru.