The “Emerging Democratic Majority” Theory is Revealed as More Progressive Bluster, by Sean Trende.

Democrats would form a new majority coalition.  This coalition would be an expansion of the old “McGovern” coalition, and would consist of working-class whites, women, African-Americans and Hispanics, as well as professional whites living in what they called “ideopolises” — high-tech areas filled with state employees and professional workers.

It’s wrong:

It’s not just that Republicans have now won four of seven elections since the book was published, although that is, as we would sometimes note dryly when I practiced law, a “bad fact.” It’s more that it is very difficult to shoehorn into the theory this election of a 70-year-old white male with a policy portfolio that is basically the antithesis of what the “Emerging Democratic Majority” recommended.  It is even more difficult to do so given that Donald Trump won in the most racially diverse electorate in American history.

Even if you could somehow account for that, I do not see how you reconcile this election outcome with the Emerging Democratic Majority theory when the incumbent president has a job approval rating in the low 50s, when the country is basically at peace, and while the economy is still growing; this is not simply an odd reaction to some global disaster.  Finally, to make the theory work, you have to find a way to explain the fact that, from top to bottom, the Republican Party is the strongest it has been since the 1920s. Whatever majority may be emerging, it does not look particularly Democratic right now.