Definately not, but US has an experience of presenting defeat as a victory. Most certainly the neocons will impose unilateral measures - diplomatic restrictions, additional trade restrictions etc. Some satellites (UK) will also join for the measures to look more impressive. The practical effects will most likely range from mediocre to none, but the media can fume them enough to save the administration face.

I still consider attacking Iran as highly unlikely - whichever way you look at it, the consequesnces even from a limited air strike will be disastrous, and I can see it only as an act of desperation. I don't really believe that people with so much (money and power) to lose would act so short-sightedly.