The current regime has certainly had a bad week.
They are wobbling and it's not easy to see an obvious successor - unless the Israelis have worked that out too! Much of the opposition was wiped out post-79, and the Revolutionary Guard will still be a potent force on the ground.
The son of the former Shah could go back and act as temporary head of state until things settle down. Let's face it, the gulf monarchies do alright for themselves, so that may be one longer term option. It'll be an interesting few weeks, although any transition will be very delicate.
I can't see it going nuclear unless Pakistan chooses that option, although that would be highly irresponsible.
Iran would be one of the first places I'd go if it became a normal country. I hear great things about the Iranian people, and the post-79 diaspora are an impressive bunch.