What happens to IS after the fall of Mosul?

With their impending defeat in Mosul, Islamic State (IS) will be left with Raqqa as their only stronghold outside of Iraq, and from where most of their leaders and commanders will likely operate. While the northern Syrian city will not fall as easily as Mosul due to the added complex environment of the never-ending civil war there, one thing is quite evident. IS will have suffered a severe setback with the fall of Mosul, which they captured in a blitzkreig operation nearly three years ago. The most urgent question now, in the minds of many, is what will happen to the group and their ambitions for a Caliphate. Will it be able to survive? Will it go underground, resurface or simply vanish? The first possible scenario is that IS will fight a protracted insurgency in Iraq. This should not come as a surprise. After the US invasion in Iraq in 2003, al-Qaida in Iraq and later IS reincarnated, and members of the scattered Iraqi army who joined IS, waged a vicious guerrilla war until their defeat in 2008. On November 2, 2016, in a 31-minute audio statement, the IS leader Abu Bakr al-Baghdadi called on the ‘the people of Nineveh’, the province in northern Iraq which includes Mosul, to stay put and fight the “enemies of God”. Baghdadi addresses “the soldiers of the caliphate” in a number of countries around the globe, including “Khurasan” (Afghanistan and Pakistan), Bengal (Bangladesh), Indonesia, the Philippines, Yemen, the Sinai, Egypt and West Africa”, among others. He states that these countries “are the pillars of Islam on earth and the poles of the Caliphate in it”, and advices them not to be disheartened with the loss of their leaders, since they can be replaced. A second possible scenario may include former IS fighters, as well as old and new adherents, to continue their attacks around the world. These types of attacks could take the form of 'lone wolf' attacks such as those in San Bernadino, Orlando, Nice and Istanbul, as well as 'wolf pack' attacks like Paris, Brussels, Kabul and Dhaka. A third scenario could see IS simply disintegrate and wither away. In order for this to happen, local Iraqis need to feel reassured that the Iraqi government will not exercise a policy of preferment of the majority Shiite population, but treat the Sunnis as equal citizens. Hundreds, if not thousands, of true followers of IS and former fighters will not be convinced of this impartiality and could decide to fight on, despite the many repeated assurances of the Iraqi government to address the various grievances of the Sunni population. There are already reports by Iraqi officials that along with middle and top-tier IS leaders, hundreds of fighters have fled Mosul. Furthermore, the remaining foreign fighters of IS have to be convinced that there are real incentives for them to return, rather than risk being arrested and imprisoned. In the coming years, we are likely to see a protracted insurgency waged by former and current IS fighters, and new recruits who are already being groomed as the next generation of IS fighters, not just in Iraq and Syria but in the wider world comprising Western countries and across Asia, Africa and the Middle East.