My guess is that Europe will be lost to the Ork invaders, or at the very least, Europe will suffer a prolonged civil war on the measure of Lebanon, the Balkans and Syria at the height of those wars. Some cities will look like Sarajevo or Grozny in their very worst moments before this is all sorted out — that is, if the Orks are going to be defeated. The Moors invaded Spain in 711 and controlled the entire Iberian Peninsula by 788. It then took 700 years, (let that sink in, seven hundred years), for the Spanish Reconquista to eject the Moors from Iberia. And the Spanish did it under the banner of the Christian cross, which was then a socially potent European rallying symbol.
Today, secular and virtually atheist Europeans will not have that rallying banner out in front to unite them in a common cause and to spur their desire for Reconquista. The Europeans will lose badly when modern Middle-Eastern urban warfare tactics are employed against them with increasing frequency. These tactics will include car bombs, human bombs, IEDs, random sniper and even knife attacks, with some Mumbai, Beslan or Paris attacks thrown in.