Just because that is its ultimate goal, as stated in the quran, doesn't mean the world will role over. Hitler also tried to take over and we no no no catted it. Islam isn't one unified thing so although it has spread in more unstable vulnerable countries usually with violence, it is unlikely there would ever be a completely unified Islamic attack in the west. They all are obsessed with fighting and killing each other remember.
What I fear is a more gradual, more silent form of 'attack'. The acceptance of aspects of sharia in our law system is one of many ways we are allowing this to happen. Coupled with immigration and birth rates I believe their will be enough Muslims in the uk to make a very significant difference into how the country is run in the not too distant future. If you think about it, it's inevitable. And whether or not you think that's a bad thing or not is up to you.
None of the 3 abrahamic faiths are unified. The only glaring difference is Christianity doesn't have an acknowledged 'mystery school' like the sufi and kabbalah, unless you accept the element and influence of jesus as an essene.
These esoteric elements are the true aspects of respective faiths, always have been, but when power, authority and greed were added the interpretation and intent of the books of the law were changed to stoke fear into non believers and to threaten external peoples.....
The literal interpretation, taking their content at face value has lead to war ever since, because people have allowed others to tell them what the words, and their meaning and intent, actually say, yet the Torah, Q'uran and even the new Testament were written to be understood by the individual on an individual level. At every moment in history, when popes, rabbis, priests and mullahs preach they do so on brand loyalty and for power retention alone.
What any of these 'holy men' say is pure bollix, the faith, it's name, are not to be presented as a generalisation, if you do, you miss the whole point spectacularly and pour fuel on the fire of your own ignorance.