"Will the US Really Experience a Violent Upheaval in 2020?"

I don't have enough information to determine if Professor Turchin is correct in his analysis.
I do know that human beings are so good at pattern recognition that we can see patterns that aren't even there.
Here's a twofer, the prediction and the follow-up.

From LiveScience, August 3, 2012:

Time evolution of issues motivating political violence in the United States.

(Image: © Peter Turchin)

Circa 1870, the North fought the South in the Civil War. Half a century later, around 1920, worker unrest, racial tensions and anti-Communist sentiment caused another nationwide upsurge of violence. Then, 50 years later, the Vietnam War and Civil Rights Movement triggered a third peak in violent political, social and racial conflict. Fifty years after that will be 2020. If history continues to repeat itself, we can expect a violent upheaval in the United States in a few years.

It sounds like pseudoscience, but it's a published theory. "My model suggests that the next [peak in violence] will be worse than the one in 1970 because demographic variables such as wages, standards of living and a number of measures of intra-elite confrontation are all much worse this time," said Peter Turchin, an ecologist, evolutionary biologist and mathematician at the University of Connecticut.

Turchin has led the development of a field of study called "cliodynamics," in which scientists attempt to find meaningful patterns in history. The endeavor flies in the face of the traditional study of history, which assumes the countless variables interacting within a society lead to chaotic fluctuations in outcomes like violence and social unrest. Massimo Pigliucci, a philosopher of science at CUNY-Lehman College, said most historians believe that "the factors at play are so many and so variable that there is little reason to expect quasi-regular cycles, or a unified theory to explain them."
But Turchin argues there is order in the chaos after all. [Infographic: Cycles Violence in the U.S.]

In the new study, Turchin, who reported his results in the July issue of the Journal of Peace Research, compiled historical data about violent incidents in U.S. history between 1780 and 2010, including riots, terrorism, assassinations and rampages....

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From LiveScience, July 20, 2020:

Mathematician predicted violent upheaval in 2020 all the way back in 2012

In 2012, University of Connecticut ecologist, evolutionary biologist and mathematician Peter Turchin made a bold prediction: The United States was on track for a chaotic, violent 2020.
Well, here we are....

....MUCH MORE