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I see six possible outcomes in order of best senarios.

1. Iran blinks and gives in. Not going to happen.
2. The West blinks and gives in to Iran having nukes. Not going to happen.
3. Britain, France and Germany (EU-3) bombs Iran's nuclear facilities. Will be like kicking a fire ant hill. The Islamist religious zealots will be swarming.
4. America joins the EU-3 in the bombings. Same as 3 above but more angry ants will be out looking to bite.
5. America bombs the sites alone. Now you have the whole Islamic community focused on America as a target.
6. Israel waits till the last moment and goes it alone and they would be fools not to. The whole Islamic world will throw everything it has at Israel and demand that the UN send all it has. In this crazy world the UN would agree to retaliation for the so called unprovoked attack.

Your outcomes pretty much lays it out.
I don't think either side will blink (eliminates 1&2)
I don't see the Europeans acting alone, especially since they know we will join in on the attack. Also, the US has the stealth aircraft that would be needed to attack anti-aircraft missile sites and deliver bunker buster bombs. Germany in particular will not join in on an attack, except perhaps with intelligence support. (#4 is a possibility)
#5 is the most likely result. I don't think that Israel alone can take out the necessary facilities, since it will be necessary to attack for some days.
There is another option, which is highly likely (#7) The UN will vote sanctions against Iran, and the one of two things will happen (a) Iran will not attack us in Iraq or attack Israel or close the straits of Hormuz, but will try to evade sanctions; or (b) retaliate with either terroristic attacks or all out attacks on the US, Israel and European interests.
I predict either #5 or #7(b)