[A] Rubicon may indeed have been crossed, with no going back to "the way things were" in Iran. That certainly seems to be the consensus. But I also wonder if it might be a bit of wishful thinking. There's a tendency to imbue events as-they're-happening as more important than they may turn out to be. To take just the color revolutions to which it has been so trendy to compare the situation in Iran: Ukraine's "Orange" and Georgia's "Rose" (not to mention Kyrgyzstan's "Tulip") were certainly major events, but the hype that they generated at the time far surpasses the attention that those countries, modestly different though their governments might be, attract today.
I think more useful comparisons would be Tianenmen or, better, the monks' uprising in Burma in late 2007. What these examples -- or even, as I suggested before, those of Kenya or Zimbabwe -- show us is the possibility of an outcome distinct from Drezner's either-or (or both) model. At the time, many thought that Burma's junta couldn't possibly survive such a brutal onslaught against the country's most venerable institution. But...it survived. In Iran, the possibilities are simply too many to predict: Khamenei may retrench, and allow Ahmadinejad to take the fall; or, the two of them may make some sort of minor concession to the protestors; or again, they could simply wait until the crowds peter out. Revolution is not inevitable. In such an interesting situation, nothing is.
As someone leery of historical analogies and fond of nuance, I would like to agree with what John is saying. Except that I don't.
First, I think it's pretty clear Khamenei is not going to retrench. The moment he said that Ahmadinejad's victory was a "divine victory," he sealed his position on the matter. He can't back down now. I'm pretty sure supreme leaders in Iran don't change political tack because of mass protests -- it undercuts their claim to be, you know, supreme leaders. In his latest sermon, Khamenei is doubling down on his bet with Ahmadinejad.
Is there any other way this ends without one camp or the other abjectly losing? I don't think so. Minor concessions will not mollify the protestors. A "compact"-like solution doesn't work terribly well here, since the factions don't trust each other enough to believe that force won't be used down the road. A re-run of the election won't work, because Khamenei's been digging in his heels and can't back down now. A straight-out Revolutionary Guards-style coup is possible, but that's going to come with a lot of bloodshed.
Second, I think Boonstra is slightly misreading my post. I'm not sure that Ahmadinejad and Khamenei will be out of power soon. What I am pretty sure of is that the only way they're going to stay in power from hereon in is through a display of brute force on a Tiananmen-like scale.
Third, Boonstra raises a valid question, which is whether a genuine regime transition would really mean all that much. Color revolutions in Ukraine, Georgia, and Kyrgyzstan have not necessarily amounted to all that much. Similarly, I see that Steve Walt has reverted to "regime type is irrelevant" arguments with regard to Iranian foreign policy.
Hmmm....... nope, not persuaded. There are two big differences in the case of Iran. The first is that, unlike all the other color revolution countries, Iran is a regional heavyweight. Every other color revolution government had to worry about a more powerful neighbor who liked the old regime better staring them down. Iran is a more powerful and less divided country. This does not mean that realipolitik pressures will not apply -- but it does mean that they are less binding than in the case of, say, Ukraine. And because of Iran's material power, a possible Green Revolution matters more in more strategic areas, like the Persian Gulf.
On the nuclear question, I take Walt's points, but I'm not sure how relevant they are after the past week. Post-regime transition governments have been quite willing to give up nuclear programs in the past -- Brazil, Argentina, South Africa, Kazakhstan, and Ukraine, to name a few. Steve cites polls that show strong Iranian support for the nuclear program -- but those same polls also show strong opposition to creating nuclear weapons.
Iran's security interests will remain paramount to any new government, of course. But I do wonder just how much of Iran's insecurity has been a product of the current regime's own making. Would a Mousavi/Rafsanjani regime be as insecure about its staus in the region?
If, on the other hand, Khamenei and Ahmadinejad manage to keep their grip on power, I can't see them ever giving up their grip on their nuclear program, no matter what is on the table in negotiations.
I'll leave this as an open question to readers -- to what extent would a post-Khamenei Iran have a different attitude towards its nuclear program?