As it is, the Democratic coalition for Presidential victories has yet to go into the area in which the Democrats have to keep together interest groups potentially at odds with each other. Ronald Reagan won big by putting together a coalition that included Southern white Democrats (then conservative on race but still loyal to the New Deal) and somewhat-liberal Rockefeller Republicans. By 1992 that coalition shattered.
The Republicans could win the Presidency with an electorate similar to that of 2010 -- but that now looks like a shrinking coalition.
Partisan realignments usually happen under the cover of blowouts.
Although I am not a Democrat, from the outside looking in it seems as if the party is comprised of many wealthy white supporters, a majority of financially successful Asians, and somewhat impoverished Latinos and African-Americans. All of those groups seem to be socially and at least nominally fiscally liberal, but there might be underlying differences between these groups that could cause a rift in the future. I don't see that happening in 2016, but eventually there could be a split in the Democratic base along these lines. The Republican party seems more homogeneous, which might be a disadvantage, as it could limit the party's potential outreach to voters who are not exactly like those who are currently Republican. Still, Republicans could have a huge victory if they peeled off at least one component of the Democratic coalition and put it in the GOP camp or simply turned one of the Democratic blocs into a swing vote. It seems like the Republicans have done this in the past with ethnic whites like Italians and the Irish, so it could be a possibility in the future.
You pointed out that the winning Republican coalition failed in 1992. I think that is true, but when you look at how Bill Clinton laid the groundwork for the new Democratic coalition, it seems to be based on style more than substance. Clinton was very liberal on many issues like gun control and civil rights, but he positioned himself as a centrist, showing that he managed to separate himself from unsuccessful Democrats like Carter, Mondale, and Dukakis based on how he was perceived rather than a significant change in policy. The only major exception seems to be that Clinton did demonstrate that he was not a tax-and-spend liberal while he was in office, cutting spending and enacting welfare reform. He probably solidified the newly created Democratic coalition by doing so, which later permitted Obama to be fairly liberal on economic issues. This might mean that even if Republicans had to change their position on the issues to win a decisive victory, they could revert back to their fundamental policies after a short time of strengthening their new coalition.
If the Democrats have a stable coalition it is paradoxically because they
don't try to expand it. 53% of the popular vote is good enough to make the Presidency very safe. I was telling people in September 2012 that Barack Obama had about a 96% chance of winning re-election because of polling that put him near 50% in just about every swing state that could have put him over the top. At least until 2024 Democrats can win the Presidency by winning
(1) all states that Democrats have not lost in the Presidential election after 1988
(2) IA, NH, and NM (NM is gone for the GOP) that have gone only once for the Republican nominee, and
one of the following:
(3) either Colorado and Nevada together
(4) Virginia
(5) Ohio
(6) Florida
(7) North Carolina
(
Missouri, or
(9) Arizona
At that I don't see how the Democrats win Arizona without also winning Colorado and Nevada, North Carolina without also winning Virginia, or Missouri without also winning Ohio.
I simply see the Republicans making no gains in the reliably Blue (Atlas Red) states. Georgia would be #10.
Indiana could be a problem for the GOP if it follows the pattern of other states in the northeastern quadrant of the US, but Democrats are not going to win it without also winning Ohio.
Republicans have so gerrymandered the House so that they have a built-in edge, but that is precarious to the extent that the Republicans run extremists in slightly-conservative districts. As I understand it an R+4 district would be well suited to a Gerald Ford or an Everett Dirksen, but not to (name disgusting Tea Party pol of your choosing. I could name 'my' Congressional Representative who well serves out-of-State interests at the expense of his district).
Maybe Democrats dream of winning the Clinton-but-not-Obama states (Arkansas, Kentucky, Louisiana, Tennessee, and West Virginia)... but that would force Republicans to start peeling off voters from the current Democratic coalition. As it is I would rather have Democrats organizing "unity of the poor" coalitions in the South to win Congressional seats.
So what is the Republican coalition?
1. Big landowners, financiers, tycoons, and business executives
2. Interests in ranching and mining
3. Christian Protestant fundamentalists and evangelicals so long as they are white
4. Most of the white middle class
Republicans face a huge demographic problem. They have had the black middle class only when it was tiny. It is losing most Asian populations irrespective of income, perhaps because it can no longer Red-bait successfully. Most significantly it is losing the fast-growing Hispanic middle class as it becomes a key swing vote. The Hispanic vote has slammed the door tight on California and New Mexico, and it may be doing much the same in Colorado and Nevada.
Democrats likely make few inroads on the large white Christian fundamentalist and evangelical vote until they cast off the gay and lesbian vote. It's too late for that.
In an economic crunch, Republicans might win blue-collar votes by promising jobs... and neglecting to say that almost everyone gets a huge pay cut and that employers get to offer workers the 'freedom' to work unpaid shifts of overtime so that they can protect themselves from being fired for failing to do so. Economic elites have often showed more sadism than charity, and American elites are no exception. Competent stewardship of the economy by Democrats could keep Republicans from making an offer to workers that they absolutely must refuse .
