There's also the issue that the majority of NATO and the US Governments have crippling levels of debt. Could they even afford to go to war? Look at the rate of debt rise under Pres. Bush Junior during Iraq. As mentioned above, going into Iran would be a much larger venture due to terrain and population.
Unless Iran actually launched some kind of attack that was successful on a Western target, I don't think you'll see another war in the near future.