Not by volition, but by jihad. Things like this, but on a "grand scale". It's also called conquest.
The same could happen to Europe - in our lifetimes. The siege is more insidious, now, being the result of two things:
(1) decadence from within - primarily as a result of postmodernist/Gramscian attack on core values and the willingness to defend one's culture; andBut the shift will be just as pervasive. They call it RECONQUEST. And if we don't fight back we cannot stop it.
(2) the deliberate colonization of Europe by Muslims who intend on making Europe become Muslim and not on themselves assimilating.