The modern Middle East is an amalgam of ancient ethnicities, religious divisions, and nation-states the borders of which were established by European colonial administrators from Great Britain and France. While those borders did succeed in instilling in each state a sense of nationalism, fealty to the state has increasingly given way to broader considerations like religious affiliation. In fact, nationalism in the sense of a shared identity is being weakened by religious extremism currently embodied in the Islamic State, which has introduced a form of nationalism entirely born of an ultra-extreme interpretation of Islam. Nationalism in the sense that it existed prior to the U.S. invasion of Iraq and the so-called "Arab Spring" that replaced old autocrats with new ones (except in the case of Tunisia, which has succeeded in establishing a genuine if tenuous democracy) has disappeared in much of the region, with the division between Shi'a and Sunni branches of Islam providing the seeds of conflict and the division between Islamist terrorist organizations like the Islamic State and al Qaeda usurping emotions formerly channeled towards nationalist or pan-Arab nationalist sentiments. The extent to which Libyans continue to identify as Libyans, Iraqis as Iraqis, Syrians as Syrians, and so on is uncertain, but the fact that Islamic State continues to recruit an estimated 1,000 new members each month does not bode well for the future.
Certainly, nationalism remains potent in Egypt, Morocco, Kuwait, and Lebanon, but divisions between Bedouins and Palestinians in Jordan, between modernizers, Islamists, and supporters of the royal family in Saudi Arabia, and even between Christians, Druze, Sunni and Shi'a in Lebanon threaten the future of these fragile political entities. The future of nationalism in the Middle East is an open question because nobody can predict with a high level of certainty what will happen in much of that vast region. Iraq and Syria will likely never again exist as they did prior to the 2003 invasion of the former and the break-out of anti-regime violence in 2011 in the latter. Similarly, Libya has disintegrated, and the sclerotic state of the House of Saud is in danger of collapsing from opposing forces of liberalism and extreme interpretations of Islam. Yemen, perpetually destitute and riven with regional, ethnic factionalism, is a mess. Indeed, Saudi Arabia is itself a microcosm of the broader Middle East, forged as it was at the point of ibn Saud's sword as the future founding king forcibly unified warring tribes and factions during his drive to establish the kingdom that would bear his name. If, as seems likely, those ancient distinctions among tribes reemerge as the royal family falters, then the nation's future is bleak.
Nationalism played a minor role in shaping the modern Middle East. British and French administrators drew the borders that became the present-day states. That is a very tenuous foundation upon which to build the depth of nationalism needed to survive the innumerable fissures inherent in the region.