The assassination of Iran’s Supreme Leader Ali Khamenei was a jolt for Iran. But its political system is built to sustain abrupt change. History shows the regime has been able to quickly find new leaders and avert crises. From Doha, Ali Hashem, a war correspondent affiliated with the University of London, tells The World’s Carolyn Beeler that US President Donald Trump’s call for Iranians to “seize this moment” and topple the regime may be wishful thinking.