Bottom line is that the global economic-financial system is so complex that it is impossible to even describe or predict much less to control, and like any such system inherently unstable and prone to sudden collapse.
Believe it or not this important idea is entertainingly explored in the original Jurassic Park novel.
The universal response to such collapse(which is almost openly advocated if you follow Krugman's arguments to their final conclusion) has been and will be global war.
Last time around it took 10-12 years to really get going(Economic collapse starting in 1929, global war in '39, U.S. manipulated into war '41)
So currently starting the fifth year of the collapse, puts us in 1934, about the time when people begin to see through the lies of the propaganda mill and realize there is no real recovery and when drastic actions begin to appear. The "bonus army" and near Coup d'etat had been violently suppressed in the U.S., there was a serious war between Japan and China by 1934 and Hitler was already Chancellor.