When will the next great financial crisis in the US occur?

Following the financial crisis of 2008 which accompanied the Great Recession, the United States government has taken a multitude of measures to reduce the risk of another financial crisis. However, it remains difficult to know how effective these measures will be in preventing another crisis or mitigating its effects once one takes place.

For the purposes of this question, a "great financial crisis" is defined by reference to the weekly Financial Stress Index of the Federal Reserve Bank of St. Louis. The index is constructed by extracting the component of principal variation from 18 different indicators of the state of financial markets using principal component analysis and is designed to serve as an overall measure of stress in financial markets. A "great financial crisis" is a crisis that's comparable to the crisis of 2008 by this metric.