I find the idea that the current level of polarization is unprecedented kind of questionable. McCarthyist purges? The violence of the Reconstruction era, which followed a literal Civil War? Compared to that people calling each other mean names seems like small potatoes.
It sort of backfired on TPTB this time around, however. Not only did they get annoying one-step-beyond-the-pale "alternatives" like Cruz, they also got legitimately different directions like Sanders and Paul. TPTB had wisely saved the easily-controlled pseudo-alternative Trump for this election, though, so he's been able to take the wind out of those sails. His two terms will be like a rerun of W's (or, frankly, O's). In eight years, though, to whom will they turn? There's no way Hillary will be able to stomach "standing by her man" for that much longer. Christie is just too fat. If you want to see the next fake-alternative president before anyone else does, keep watching those reality shows!