Why do I assume that air strikes against Iran will be ineffective, especially given the sad shape of the Iranian economy and its weak military capability? 
My answer: because everything Bush has done for the past seven years indicates that the strikes will be limited. The Iranians have had years to dig in deeper. Bush will never use the force needed to end the threat. Had he wanted to do so, the time was 2002.
The strikes will not be directed at what should be the primary goal: ending the existence of the Iranian government. Ineffective strikes–meaning, strikes that hurt Iran militarily, but did not topple the government–would very likely lead to a nationalist reaction inside Iran. The regime would link this Persian nationalism to the Islamic revolution, and claim victory in the confrontation with the Great Satan. This could actually strengthen the regime, both internally and in its relationships with international foes of the US.
Wars are fought when people make the decision and commitment to fight. Military capability is a function of this commitment, which, for a major conflict, is always moral in nature. Iran is particularly dangerous because it claims the moral force of a religion with over a billion believers. Iran also links that moral force to Persian nationalism, which can bring support for the regime from those who might otherwise oppose it.
Ineffective strikes–meaning, again, strikes that allow the regime to continue to exist–will in the minds of those believers demonstrate the power of the regime and the failure of the US.
An historical parallel is the Tet Offensive in Vietnam. The North Vietnamese forces were utterly destroyed. They had nothing left– except the claim that they had attacked American forces and survived. But this military defeat was a propaganda victory, which demoralized the US and elevated the stature accorded to the North across the world. The US did not destroy the enemy government , and in time lost the war.
In 1975 an American colonel said to a North Vietnamese colonel: “You know you never defeated us on the battlefield.” The NV colonel replied “That may be so, but it is also irrelevant.” (Harry Summers, “On Strategy” p. 1) Tactical victories in *battle* were irrelevant to the outcome of *the war*.
Without a forthright statement of our moral right to defend ourselves,followed by a policy of enforcing this right, the US will be unwilling to do what is necessary to destroy the Iranian regime.
All we will be able to do, as I wrote earlier, is hope that the Iranians overthrow the mullahs themselves. We waited for this under Carter as well.
 George W. Bush’s Empowerment of Iran by John Lewis (November 2, 2008)