Interesting idea. That will be an interesting study many decades from now when we have entire lives of Internet usage to study. I wonder if web site populations, particularly the ones around news/commentary forums such as HN, slashdot, reddit, etc., as a whole migrate from one site to the next as a collective or stay married to single sites. I'm curious if it's the same for social media sites too? My prediction is that the sites will stick around, but different age groups and populations will adopt different sites in somewhat unexpected ways in the same way that fashion or music fads reemerge with populations without warning; that people choose their site/community based on their friends, social allegiances and/or aspirations rather then the "tech" of the site.
I also think its fascinating to think about where the source of "news" or some type of idea, picks up critical mass to become viral. Are they concentrated to tiers of sites for example?
