The petrodollar system resolved the 70s inflation crisis after Nixon sent the head of the CIA to Saudi Arabia. The US military backed revolutionaries during the arab spring because the dead dictators wanted to start a pan-african currency with which to trade oil. Iran, Venezuela and Russia were under sanctions and treated as enemies in very big part because they were selling oil for other currencies than the USD.

The US dollar is propped up by constant US dollar liquidity related to the fact that you need it to trade significant quantities of oil with the vast majority of producers. That situation was held up by the US' military might. Starting shit with Iran and being unable to finish it means there's no reason for oil producing countries to keep financing american debt on the cheap. What are they going to do? Restrict their own access to crude?

There's more to it, but the USD for gas scheme is a big structural chunk of the financial house of card. You break that and the rest won't hold up very long. And it's not like other structural parts of what makes the USD the global reserve currency aren't getting eroded either. Fed independence stands there glaringly obvious.