This chart above that I made is a little bit of context for claims that Republican operatives were surprised to see the white share of the electorate down from 2008 rather than up. Their theory, I guess, is that putting Obama on the ticket led to a one-off increase in minority voting that would head into reverse when he ran for re-election for some reason.
The truth, however, is that there's no discernable "Obama surge" of minority voting here at all. The white share of the electorate has evolved as far back as exit polling is available in a pretty steady fashion. The only year in which the white share rose was 1992. Ross Perot, not Barack Obama, was able to reshape the electorate by perhaps engaging some set of disaffected white people who are totally tuned out of the regular political process. Be that as it may, there's no secret Obama sauce in this—it just reflects the evolution of the country. In any given year, the cohort of new 18 year-olds is less white than the national average and the cohort of people who die is whiter than the national average.
White identity politics is just a political strategy whose effectiveness is in terminal decline.