One word: subcultures.

I think we'll see an expansion to most of the First World of the trend we see in cities like San Francisco, where the Internet has allowed people to organize niche cultures (steampunk, furries, pyromaniacs, etc.) like never before. I think that, by and large, people would prefer to seek out a smaller culture based on a common idiosyncratic interest if it were an option, not least because rising in status there is often easier than getting noticed in the local mainstream culture. I think that the main reason the mainstream culture is presently so large, therefore, is because it's hard for a juggling enthusiast in Des Moines to find like-minded people.

I expect that over the next 10 years, more and more niche cultures will arise and begin to sprout their own characteristics, with the measurable effect that cultural products will have to be targeted more narrowly. I expect that the most popular books, music, etc. of the late 2010s will sell fewer copies in the US than the most popular books, music, etc. of the Aughts, but that total consumption of media will go up substantially as a thousand niche bands, niche fiction markets, etc. become the norm. I expect that high schoolers in 2020 will spend less social time with their classmates and more time with the groups they met through the Internet.

And I expect that the next generation of hipsters will find a way to be irritatingly disdainful of a thousand cultures at once.