The biggest effects would be economic, and would drive any sensible country away from a reliance on Gulf Oil.

The US is essentially a military/petro-oligarchy wrapped inside a republic pretending to be a democracy.

If the global oil economy is badly damaged, the US will be badly damaged with it.

This isn't about who can blow the most shit up. It's about global standing in the economic pecking order, which is defined in part by threat credibility, but also by control over key resources.

If some of those resources stop being key, that's a serious problem for any hegemon.

We're seeing a swing towards global decarbonisation, and this war is an ironically unintentional turning point in that process. The US has had decades of notice that this is inevitable, but has failed to understand this.