Wikipedia’s definition of subculture-
In sociology, anthropology and cultural studies, a subculture is a group of people with a culture (whether distinct or hidden) which differentiates them from the larger culture to which they belong, for example, if a particular subculture is characterized by a systematic opposition to the dominant culture, it may be described as a counterculture.
Commercial sub-cultures are put to pasture in the place where they’ve spent their whole existence trying to avoid — the mainstream. It’s simple inevitability. The mainstream devalues subcultures for it’s own gain by using their appeal to certain markets as a tool to further their own agendas. This is particularly apparent within the advertising and entertainment fields.