If you don't see the common theme, allow me to explain: failed or failing states are bad juju, for both the international community (can you say, "peacekeeping operation?") and the states immediately adjacent to the problem area. A weak state is like a black hole, with the gravitational pull to drag in and crush anything nearby.
With that, should Iran's government evolve over time into a moderate and open minded Islamic state, that would be a good thing; should Iran fall swiftly and violently, we'd have three states in a row (Iraq, Iran, Afghanistan) riding the bleeding edge of domestic catastrophe.
Thus although I don't agree with Iran's stance and thinkit would move forward as a nation by showing some good old-fashioned acceptance, I'm not in a hurry to see the Iranian government shift so radically and swiftly that it collapses from overextending.