How long can the Saudis hang on with cheap oil?

Mark the date on your calendars: Aug. 28, 2018. That's when Saudi Arabia goes broke. Or at least that's the date according to one model of the oil-rich nation's reserves, crude production and the price of oil. If crude stays around $40, America's Middle Eastern ally will run out of money on that date. Obviously, that assumes no other changes in fiscal or monetary policy. But regardless, it's ...