Europe has a bloody history and talk of how Europeans have lost the ability to fight is short-sighted.
Ours is only the latest generation to imagine that brutal warfare is a relic of the past. In 1851, Edward Creasy wrote, "It is an honorable characteristic of the spirit of this age, that projects of violence and warfare are regarded among civilized states with gradually increasing aversion."
He could write that conclusion since no major European war convulsed the continent since 1815. Yet 36 years without war did not mean that Europeans were permanently pacifists despite that growing aversion in civilized states. The Crimean War of 1853-1856, the Austro-Prussian War of 1866, the Franco-Prussian War of 1870-71, and the Great War (though they still had the honorable spirit of the age to believe it was the war to end all wars. Only later would it be World War I.) were yet to come. The Russians and Turks went at it yet again in that time, too.
So let us not worry too much about what the Islamic world will do to Europe. I think Mark Steyn is right to worry about the demographic trends in Europe, but I don't believe that the native Europeans will always act as they do today. Europe may be able to ignore the threat for a while, but I am confident that the Europeans will react with savage fury when they finally perceive a threat. They have a talent for war, remember. Worry for the Moslems who will be swept up in a campaign againt the Islamists who believe they've found the perfect target--rich, soft, and guilt-ridden.
The Europeans will--eventually--do what it takes to destroy the jihadi threat to Europe.