The only way it would work is if the US, China, and other major economic powers all agreed to enter a hyper-inflationary period (which looks as if will happen). We'd probably see the collapse of the monetary system at some point during a full-scale war, though, all world debt canceled, and then the monetary system replaced by some other currency.
But could a pre-emptive strike on Iran result in a full-scale war? Probably not. Iran would probably just get hammered in a swift war; their regime would be changed; hardliners removed from positions of power, and then there would be 20-50 years of ongoing occupation / reconstruction efforts, hopefully more successfully than whats currently happening in Iraq and Afghanistan.
China and South-East Asia, Middle East, Russia, and India, South America, and Africa, if they go along with this universal hyper-inflationary period would jostle to find ways to suffer the less than one another, ultimately placing the majority of the burden on the North American and European economies.
Those countries which would not go along with the hyper-inflationary period, would probably find themselves at war with those nations that would go along with it.
The likelihood of a world war flaring up, therefore, would depend on which countries / regions would adopt the hyper-inflationary fiscal policy agreements and which would not.
In a sense, you could say that those who would refuse pay the US to be the world's police-force and stomp out terrorism and rogue regimes would find themselves enemies of those that would.