Jonathan V. Last writes about demographics for The Weekly Standard. Here he focuses on two trends active in the last election: the increase in Hispanics, and the increase in singles.
Last makes the point that the increase in Hispanics is real but its long-term importance has probably been overrated. See his analysis for why this is so. On the other hand, he views the dramatic increase in singles as being of particular importance.
As we know, Democrats' programs appeal to singles more than they do to married people. What if anything the GOP might do to counter this trend becomes an issue for discussion. Last suggests that Republicans try to get more people to marry, rather than to offer goodies to singles.
The intersection of reliable birth control with the declining importance of religion has 'legitimized' cohabitation, or at least reduced its illegitimacy. Speaking of newlyweds, "How long did they live together?" is the new equivalent of "How long were they engaged?"