How would the world look today if the 9/11 attacks had never happened, or had failed? Islamic extremism and terrorism predated 9/11, and many of the sources of conflict would have existed regardless of the outcome of the attacks, so you can’t reasonably say we would be living in a world without Islamic terror. On the other hand, the magnitude and visibility of the threat probably would have been much different.
ISIS and Iraq are part of the same poisonous package. It is clear that Bush 43 and his neoconservative friends wanted a war with Saddam, and that the ostensible rationales for the war had little logical connection with 9/11. On the other hand, 9/11 was an essential part of the psychological climate that created support for the invasion, and Bush and Cheney occasionally made false references to Saddam and terrorism in making their case to the American people. Would the Bush Administration have found a pretext for war with Saddam that would have mobilized the American people without 9/11? Or, to put it another way, would Saddam have eventually done something stupid and aggressive enough to sell the war to the American electorate?
I don’t have a definitive answer to that. To me, it is a 50:50 proposition.