What if They Gave A Revolution But Nobody Came?

Bernie Sanders wanted a revolution but it appears that no one read the memo announcing it.
The hallmark of the Sanders’ presidential campaign was to defy conventional wisdom held by mainstream political science and political operatives.  This wisdom depicts American public opinion and voters as plotted along a bell curve from political left to right, with the median voter at the center.  The theory says that most voters are in the political center and that the battle for victory in presidential elections is to move to the center and capture the five or so percent of the electorate who are swings, especially in the critical presidential swing states that will determine the electoral college victory.  This model recognizes that perhaps only about 55% of the electorate votes and that it would be extremely difficult to bring new voters into the voting booth.
Sanders’ campaign challenged that.  The allegation is that the electorate is less of a bell curve and one that has become bimodal with a decreasing percentage of the voters located at the center.  The median voter still exists but largely is immaterial given the polarization and shift in American public opinion.  It is also a model that says that effectively swing centrist voters have  disappeared and racing to the center to find them is futile.  Better to try to mobilize many of the 45% who do not vote.  These are young people, people of color, urban liberals.  They chose not to vote because they do not like the political choices or policy options they are offered. 
These non-voters, the theory goes, face an empirical reality different from voters.  Capitalism has not been kind to Millennials and Gen Z.  They face a wealth gap, high college costs, high housing costs, and an expensive medical and health care delivery system their Silent, Baby Boomer, and Gen Xers do not confront.  They are America’s future.  Speak to their concerns and issues and you move American politics to the left and build a movement and party for the future.
There is a lot of truth and empirical evidence to support Sanders’ theory.  The electorate has become bimodal.  There is evidence of a decreasing number of swing voters and the reality of the median voter.  The political attitudes of Millennials and Gen Z are very different from that of Silents and Boomers.    The problem seems to be the last leg of the theory–mobilize the young and non-voter.  This is not happening for Sanders this year.
We know now according to Pew Research that the Millennials this election are now the largest generational voting bloc, surpassing the Baby Boomers.  Millennials and Gen Z together are now 37% of the electorate–the 2020 election is the beginning of the end of the political era for Baby Boomers, and perhaps the last hurrah for the Silents.  Yet so far, younger voters have failed to turn out in the caucuses and primaries, with voting rates less than what they were in 2016. On average, turnout among younger voters is about 25% less than it was in 2016.  Why is Sanders’ revolution not happening?
There are many reasons.  First, he is an independent running as a Democrat and his politics is not within the mainstream of the party and so far the Millennials and Gen Zs are not in control of the party.  In fact, they do not like the Democratic Party as presently constituted, seeing it still as controlled by the Boomers.  That alone could be hurting him.  Two, he has done a bad job expanding his political coalition, including a failure to bring on African-Americans.
Moreover, Sanders might have done so well four years for three reasons not present now.  By that, many voters did not like Hillary Clinton and a vote for him was a protest vote.  Two, Sanders did well in caucus states (because the smaller numbers in those states favored a fervent few) and there are fewer of them this year.  Three, the depth of Democratic Party anger to beat Trump is greater this year than four years ago.  Pragmaticism might be prevailing.
There are other possibilities.  Perhaps it is too soon for the revolution.  Godot has not arrived and we need to wait for more Boomers to die.  Some claim voter suppression, but there is not a lot of evidence that accounts for the dramatic voter downturn.  The rejection of electoral politics may be a factor, but rallies go only so far in an electoral political system.
Conventional political science and politicos may be wrong about the bell curve, median voter, and swing voter, but they still seem correct in regards to the difficulty of motivating the non-voter on the left.  Sanders is not crazy to look to bringing them into the political system to build a movement, yet his failure is that of not being able to figure out how to do that.  Where he and progressives need to go is to identify the real barriers to their disengagement and then determine the ways to bring them in politically.  Should the Democrats or a third party not do that longer term, America’s electorate will shrink dramatically over the next few years, perpetuating a base of voters who are not representative of the majority.