I have to slightly disagree:

It is no longer just the Extreme right that is upset, they have always been upset, same with the Extreme Left...

You have the Majority in the center that is upset, and that does not bode well..

To claim that it is the two polar opposites on the Left and Right pulling in either direction, I find to be rather naive and possibly a root cause of the real issue

There is quite a bit of simple outrage at the Establishment Politicians for not doing what the people elected them to do rather then a fundamental shift in thinking ..