No doubt that what Daash is doing in Iraq and Syria are acts of hateful sectarianism and terrorism. Yet, they should be taken as example of what similar organizations may do in other countries.
It’s known that they aim to restore the Islamic caliphate, but they should realize the costs of the wars now are completely different from the wars 1400 years ago. In the past, they only used swords and spears, and ate what they found in the way. But now the weapons are so expensive, and the richest countries can’t afford the cost of the wars for long.
Additionally, the general mobilization of armies costs billions of dollars just to afford food and drink. Moreover, and the nature of the wars currently makes the industrialized countries of the weapon are getting the real booty, but the warriors themselves do not get anything.
Another important point in the question of the Islamic caliphate is that they used in the past to invade rich countries and use their money to financially support their wars. However, Daash now is aiming to invade very poor countries like Syria and Iraq.
The real danger of Daash is trading on racism and sectarianism, which proved success in mobilizing fanatics and extremists throughout history. Those fanatics fight like animals and invent inhumane ways to kill their enemies, just like Hitler did with the Jews and Daash do with Shiites and Christians in Iraq. Unfortunately, those extremists are many in the Arab world!