Muslims probably think the attacks on September 11th were a great victory, but I think history will reveal that event as the beginning of the downfall of Islam. Prior to that, the world could pretend that Muslims were peaceful, if backward, people who wished to peacefully co-exist with others.
After 9/11 the world rightly sees and understands that Islam is imperialistic and authoritarian and a serious threat to peace, culture, and democracy anywhere it invades. And I think it's no accident that there's been a creeping invasion of Muslims in all areas of the world over the last 10-20 years.
I agree with your analysis. 9/11 may have been a tactical victory for Islam (just like Pearl Harbor was a tactical victory for Japan); but it was a strategic blunder. The West is beginning to awake; when it united, when Russia is brought completely into the fold, Islam will quake in its boots.