In a post-American Middle East, this kind of concert of powers is the only way to stop the bloodshed. But my instinct — after talks with Iranians and Saudis over the last few months — is that the prospects for a grand bargain are some way off. Although both sides are frightened of an uncontrolled escalation, they have both gained power and prestige from a Middle East split along sectarian lines. Neither side is yet exhausted by the proxy wars or satisfied with the current balance of power. The potential rewards still outweigh the risks of the struggle, particularly for Saudi Arabia, which sees the conflicts as a means of reversing Iranian hegemony in Syria and Iraq.