Vladimir Putin's new presidential term is just beginning, but it increasingly looks like the beginning of the end.

Whenever Russia's people pour into the streets en masse, as they currently are doing, from that point on things never work out well for the authorities. In 1917, Russian Emperor Nicholas II had to abdicate in the wake of mass street protests, clearing the way for the Bolshevik Revolution.

In 1991, the Soviet Union — then seemingly an unbreakable monolith — collapsed in just a few months. Hundreds of thousands went into the streets to confront the hardline coup against Mikhail Gorbachev's perestroika.