That is a hope. However, Secretary of Defense Rumsfeld reminds us that hope is not a method.
Now, let's run a hypothetical exercise: you destroy Mecca, Medina, Qom, and the Dome of the Rock.
Islam doesn't crash. But now, instead of Islamism being a very extreme minority that mostly kills Muslim, it's now close to 100% of the world's Islamic population.
Now what?
The Marine's credo --Kill `em all and let God sort `em out.