By Election Day 2016, ambitious Democrats had already resigned themselves to an eight-year wait for their chance in the national spotlight. Hillary Clinton was an overwhelming favorite against Donald Trump and, assuming she won, running a primary challenge against her in four years would be a fool's errand.
Then Clinton lost.
While this most stunning upset in modern presidential history has produced (and will produce) a thousand aftershocks, one of the most unlikely and important is that the Democratic presidential nomination in 2020 is now open.
That opening is made all the more remarkable by the fact that there is simply no logical heir (or even heirs) to President...