One option is when a critical mass of her enemies is reached such that turning on the Clintons is seen as a safe alternative to kissing their butt. This may or may not happen in her first term.
Failing that, she could lead us into WWIII in the Middle East. Or exchange a couple nukes with NK or Iran. Or plunge the country into depression with massive tax increases.
My guess, more likely, is she sits fiddling while our cities implode with levels of racial violence not seen since 1968. Or the country fissures along the coasts; basically the classic "Blue Atlantic/Pacific vs. Red Interior state map you see the pundits show.
So yeah, not good.