This is a bigger issue then Israel and the USA having to worry about, it's going to affect one fifth of the worlds oil supply which will cause mayhem in global economies which are already in serious problems following the credit crunch and global recession.
If this war was to happen, which I believe it will after America has finished it's elections in November. This will be the whole of NATO pretty much unleashing hell on Iran just like the second Gulf war.
Do I think Iran stands a chance? No, there is not one country in the world that can defeat the combined forces of NATO.