From the National Interest (found via Google News)
Some Europeans that I have spoken with privately feel that, for the next two years or so, Europe can afford to continue to support Iran’s economic isolation, but that, starting in the next decade, growing pressures to secure new supplies of energy will lead more European firms to begin investing in Iran to ensure that, by the 2020s, the infrastructure is in place for large-scale Iranian shipments of gas to Europe.
I pressed my interlocutors further—was this is a case of advising, "Whatever you do, do it quickly"—meaning that if the United States were to pursue forcible regime change the preference would be to do it sooner? They demurred. But the underlying impression I received was that, say, by 2011 or 2013, large-scale European investment in Iran will begin no matter whether it is still the Islamic Republic or some other form of government—and that Washington is faced with two clocks counting down with regard to its freedom of action vis-à-vis Tehran.
Iran is in a fairly strong position right now. If sanctions are increased, they will hurt the Iranian people, but they will not hurt the regime in Tehran, they are much more likely to strengthen it. A military attack can accomplish military aims, but they will have the political consequence of strengthening the Iranian regime and weakening the US' regional position.
If this article is correct, and pressure on Europe to deal with Iran will increase dramatically in the medium term, then Iran is likely to wait the US out until that time.