I don't doubt that we will win in the sense of being able to contain the threat at a level that will allow the West to continue to survive and prosper.
However, we will not completely eradicate Islamic fundamentalism, and it may in fact get much worse.
I fully expect further attacks at least on the scale of Sept 11, and I think top defense officials do, too.
The West has been under threat from Islam for over 1300 hundred years, and I just don't see it going away in our lifetimes.