The Islamic State of Iraq and Syria, or ISIS [the U.S. government prefers "so called" Islamic State of Iraq and the Levant, or ISIL] is almost exactly like the early Saud family proto-state that eventually became Saudi Arabia.
So it could be argued that the U.S. should stay out of the mess. If we are okay with Saudi Arabia, we should be okay with ISIS.
U.S. governments have long pandered to the dictatorship in Saudi Arabia. Barack Obama is just the last of a long line of Presidents who have no problems shaking hands and forming coalitions with the Saudis. It does not matter that they are undemocratic, oppressive, women-hating, religious fanatical thugs who finance terrorism. They are strangely pro-American undemocratic, oppressive, women-hating, religious fanatical thugs who finance terrorism and help America in many ways, like being friendly with Israel.
The Saud's emerged from the mess the British Empire made in the Middle East. You'll recall that the British Empire was built by undemocratic, oppressive, women-hating, capitalist fanatical thugs who were not satisfied with conquering Wales and Ireland. No, they were clearly not going to be satisfied until every nation in the world was enslaved. After they grabbed much of Africa, including Egypt, they turned their greedy blue eyes to the Middle East, which until World War I was ruled, more or less, by the Ottoman Empire (an Islamic empire with its capital in Turkey).
The Brits promised the Arabs that if they would just fight against the Ottomans, they would be allowed to set up a Arab state that included the entire Arabian peninsula as well as the Arab majority parts of Palestine and (what are today) Lebanon, Syria, and Iraq. They also promised Palestine to the Jews and Lebanon and Syria to their French ally. The Faisal family, who ruled around Mecca and Medina on the west side of the peninsula, took the bait.
The Saud family, putting themselves at the head of Islamic religious fanatics known as Wahabbi [who make the ISIS guys look like Quakers], decided that they would smile at the British, take their offer of arms, and use the war to extend the area of their tribal rule in the central peninsula
When World War I ended the British took Iraq and Palestine for themselves, set up puppet governments [including the Saud area of control] here and there, and gave Lebanon and Syria to the French imperialists. This discredited the Faisal family. By 1932 the Saud's army of religious fanatics (remember, this is to show they are like ISIS) had murdered pretty much everyone who opposed them. The Faisal family got British protection in Jordan as a booby prize.
You have to admire the Sauds, though, in the same way you would admire any highly-effective predator. When oil was discovered in 1937, Ibn Saud double-crossed the British and gave the development rights to American oil companies.
The pro-American nature of the Saud family has always been practical. America has always been the Christian imperialist predator most removed from the Saud terrain and most willing to provide arms to a totalitarian Islamic regime.
It does not seem likely that ISIS will be able to repeat the Saudi feat of establishing a "permanent" radical Islamic state, but then again they might. You can see why the Saudi fear ISIS as much as they fear Iran, Shia in general, and anything that might stir their 30 million or so people to revolt against them.
The problem for ISIS is they are not duplicitous enough. They could get further by using the same strategy of combining diplomacy with militancy that the Saud used. They could also have been more forgiving of their Islamic neighbors, encouraging people to convert to their own particular brand of craziness, rather executing people just for being Shia or whatever.
There is something known as survival bias. We know about the Saud and Wahabbism because they survived. We have forgotten the many Arabic tribes that once rivaled or even dominated them. Perhaps ISIS will soon be bludgeoned back to hiding in caves and basements.
But I would not bet on that,either, not yet. There is a slim chance that the Sauds, not ISIS, will be history in a few years. Trying to appear to be the leaders of the Islamic world while actually breaking bread with the Israelites and Americans is quite a balancing. The Sauds have grown fat, and the entire country knows how corrupt and un-Islamic they are behind closed doors. On the other hand, being fat and un-Islamic probably appeals to quite a few people.
However much the current leaders of ISIS may pontificate, they will go through the usual curve if they survive and prosper. They will maintain a radical Islamic front, and grow a fat un-Islamic rear end.