What this means, as Edsall points out, is that the Democratic coalition will now be composed of two disparate groups: Highly educated white liberals on the one hand, and minorities on the other. Notably, there is no real ideological coherence in terms of unity of interest that can emerge from the match.
Notwithstanding the increasing number of minorities in the United States, it strikes me that keeping this coalition together will present problems for the Democrats -- and, indirectly, for the country. The problem for the Democrats is that their two groups are ideologically incompatible on many scores: The white liberals care mostly about left-wing social policy, while many minorities are socially conservative. And there may come a time when even white liberals acknowledge that limits should exist to the concept of "spreading the wealth around" in order to pay for ever-more-massive public spending, right now often (but not always!) supported by minority groups.
Should this two-part coalition begin to splinter, it may improve the chances of Republican electoral success, but it will cause ugliness in the country. Why? Because with no thematically coherent agenda, and in their desperation to keep minorities within the party fold, Democrats will continue (and escalate) their efforts to paint Republicans -- and America itself -- as racist so that they remain the only perceived choice for minorities. Division -- and, ironically, instilling fear of the (conservative/Republican) "other" -- will be the key way for Democrats to hold their party together.
It's an ironic reversal of FDR's injunction about having to fear only fear itself, isn't it? Even so, Democrats will probably calculate that it's easier to hold the coalition together by playing the race card than it is to convince affluent, well-educated white liberals to accept a slower pace of social change -- more acceptable, usually, to minorities.
All this, of course, is a challenge -- and an opportunity -- for Republicans. No, not to embrace left-wing social policy to win back educated white liberals -- but to find a way to appeal to minorities without simply promising more redistribution of wealth, a la the Democrats. And it's going to take a cultural shift to precipitate this political one.