They're not gonna do anything, all of world is helping Iran and has helped it by overthrowing Saddam and US/Russian intervention in Syria/Iraq when they almost fell to militants in 2014. EU/China/Russia are helping Iran economically/militarily. Iran also has ties with India/Turkey and other powers. World has never formed an international coalition against Iranian sponsored Shia militias whatsoever. As Shia's are a strategic asset for them against Sunnis. On other hand, world has attacked almost every Sunni militia that arises.
Now you may say because these Sunni militias are irresponsible and I agree. However, an responsible and civilized Sunni Islamist united front is still going to get attacked by the world as world does not Sunni Islam and Sunni Muslims to prosper in their own region as they have historical scores they want to settle with them.
Iran is nothing without whole world+Arab regimes helping them. Same with Israel. If there were good Sunni Muslims that arise into political scene, God will support them against whole world and nothing will stop them from establishing worship of God in their own lands and securing their lands from foreign terrorism and demons with genocidal intent towards Muslims.