The petrodollar confers a huge advantage to the US, which is the whole point of it. It soaks up liquidity and allows the US to export inflation which allows it to be in the insanely profitable business of printing money. An argument could be made that this is corrupting and economically distorting to society resulting in a net negative but there is no guarantee that the same corruption would undermine China in a timely manner. I think the effect would be rather muted provided that the US remains world hegemon but if the US would lose the petrodollar and credible force projection at the same time we will shift from the current looting stages of collapse to the free for all stage of collapse. Or put another way, from a managed decline to an unmanaged decline.