Two Different Waves of the Future
The left still regards itself as the Wave of the Future. They can buttress that by pointing to the support of the media and academia (which are of growing importance in society) and the tendency of many immigrant groups to vote Democratic. An essential part of that self image is the support of Jewish voters. Jews are disproportionately involved in media and academia and are regarded as an immigrant group (even when third generation) by mainstream leftists and allegedly right-wing loons.
On the other hand, we see the fact that people in more traditional households vote Republican and are out-reproducing the Enlightened Ones. These two tendencies collide in the Ultra-Orthodox community which is both Jewish and traditional. If the left can get the support of the Hasidim, they can continue to pat themselves on the back.
It looks like the Democrats lost Hasidic support this year.