You forgot the most probable end: Total global financial collapse from endlessly printing money. Leading to hyperinflation as the global reserve currency (US dollar) starts to look like the Zimbabwean Dollar.
Thus leading to the bankruptcy of the welfare state, where as, the poor and by now the total lack of middle class, having nothing left to lose, unleash massive civil unrest. Bringing the modern industrial world to it's knees!
Or
Thus leading the world powers, with rising discontent, and a glut of young, unemployed, draftable, citizens, to initiate hard line stances on foreign policy issues. Leading to a conventional World War on an unprecedented scale.
Or
You know, Aliens, from Mexico, now classified as invaders, using all those great guns we sold them in fast and furious...