Thanks for the link! I didn't know there was already a version of this theory out there, and I didn't know the actual figures.
So what do I make of this data (assuming the veracity of the Wikipedia summary, since I'm not dedicated enough to read the papers)? Well, I'm surprised by it.
I'm not especially surprised. Aside from possible confounding factors like the rise of Free & free stuff (strongest in subcultures) which obviously wouldn't get counted in commercial metrics, technological and economic development means that mass media can spread even further than Internet-borne stuff can. cue anecdotes about Mickey Mouse posters in African huts, etc.
The subcultures seem to me to appeal mostly to the restricted 1st World wealthier demographics that powered the mass media you are thinking of; one might caricature it as 'white' stuff. It...
I would like to propose this as a thread for people to write in their predictions for the next year and the next decade, when practical with probabilities attached. I'll probably make some in the comments.