You have a point, though not the one you mean. One cause of polarization may be that a larger number of Americans than ever before in our history would agree with my statement in post #69 (which I have stated often before on this board). Not a majority, but more than ever before. I’ve often read that “atheist” or “nonreligious” is the fastest-growing religious self-identification in America recently, and the group who would agree with me includes a great number of religious people as well. While at the same, time social/religious conservatives are fewer than ever before – no longer a majority, but still a very large minority. See the Pew Political Typology 2011. The “Staunch Conservatives,” the “highly engaged Tea Party supporters,” are the oldest group demographically, (61% ages 50 and older). They are declining, and they’re anxious, and they’re angry, and they’re not going away without a fight. And now, to a larger extent than ever before in history, they face a highly significant number of young Americans holding values not merely different from their own but in many respects diametrically opposed.
Well, I’m sure abortion will still be an issue in 20 years, that’s a special case going to the heart of America’s moralistic character, on both sides. But it won’t be a hot-button issue any more – as mentioned here, while the range of pro-and-anti opinions has not changed recently, their political salience has declined, people will be less likely to vote on them in the future. And the others will simply go away. Most Americans 20 years from now will wonder why SSM ever was an issue, and place centuries of antigay prejudice in the same old-shame bin as we now place anti-black racism.
But that’s only part of the picture. There are three basic poles/axes in American politics: social/cultural; economic; and foreign/military policy. Some issues, like immigration, touch on more than one, but those are the poles. The social/cultural pole may simply become less polarized as the generation now in retirement passes away; I see no particular social-values-divide emerging between GenX and GenY, or within either. The economic polarization may be more intractable – every American generation is internally divided on basic assumptions of economic policy, values and justice (note the Pew Typology now has a category for “Libertarians”); and, of course, every American generation is divided by class; and on this pole the political phenemena are conditioned not only by the economic beliefs of the people, nor only by their personal economic interests, but also by the vast influence of vested economic interests, big-biz, megacorps, on the political process and message. And that’s not about to change.
As for polarization on foreign-military policy – appears to be declining in salience, except in all the important ways it affects the economy, see above.