The Iranians suffered approximately 200,000 battle deaths during the eight years of the Iran Iraq War without quitting. It took the combined shock of the USS VINCENNES shooting down an Iranian airliner and Iraq's massive use of nerve agents to retake the al-Faw Peninsula that convinced the Ayatollah Khomeini to agree to a cease fire, and only he had the moral authority to call a halt to the bloodshed, which however also left his regime intact.
This is probably a good indicator for the short term.