Death of the mainstream?
Maybe this is due to the splintering of popular culture into so many little niches. In the age of mp3s, netflix, amazon et al, there's so much access to media beyond what's mainstream that it's hard for one dominant culture, musically or otherwise, to emerge.
An interesting statistical idea behind this shift in cultureal representation is that of the "Long Tail." Here's the article from Wired Magazine that first used the term in that sense. It's pretty interesting stuff. Maybe we're truly witnessing the age where nothing exists culturally but splintered pastiche, echoes of former movements. It seems that's part of what you were saying a group like Gorillaz embodies, Andy, which is why I think they are a particularly interesting example within today's popular music.
