A massive slap to the world's only superpower. It's ok to say what you are saying but the loss of prestige to the Americans will be telling.
The Americans for all their bluster are not invincible and have much to lose in the region. The attack on the Saudi refinery was but a small gesture in this direction. If the Americans and their cheerleaders think that Iran will be a walkover like Iraq and Afghanistan are way off the mark. Any war with Iran will set the region on on fire and the Arabs will be shitting their pants as we speak.
You will see plenty of back pedalling in the days to come.
The Iranians, regardless of whether any Americans died, have thrown down the gauntlet. It's up to the Americans to pick it up.
I bet they don't.