I think the end of musical subcultures may be significant. It used to feel like there were many isolated musical bubbles, separated by geography or language or social class or simply aesthetic choice, and each one would develop its own unique musical idiom. Every now and then some cultural explorer would bring one of these idioms back to the mass market, introducing a new flavor into the pop music melting pot, and a surge of innovation would occur.
Of course the flow of attention back into the previously-isolated musical subculture tended to be destructive, as far as its inhabitants were concerned; the musicians who rode the wave out to mainstream popularity were often scorned and labeled sell-outs, for making private profit at the expense of the community which had supported them.
When there is no more isolation, all music shared everywhere over the internet all the time, how can a unique new cultural strain develop? When any new ideas one musician comes up with just get dropped into the global soup, instead of taking time to ferment in a smaller, more focused environment, how can any distinct new genre emerge? It seems like we are seeing a different model of musical creativity, which is likely to be broader and smoother; more gradual global drift and fewer irruptions.