IMHO the fundamental problem is that the world wanted dollars so they gave the US gold or stuff for those dollars. If that flow ever reverses then there's problems. Bretton woods solved the gold issue. The plaza accords solved it when Japan was the problem.

Today the solution is that foreign countries but government debt. That will last as long as everyone is willing to roll it over. It's not clear how or why that stops. But if/when it does it's not going to involve the US sending out trillions worth of stuff

No the fundamental problems was the econmists at the time believe in fixed exchange rates and that's why the got suckered into Bretton woods despite it being a crappy deal, specially for Britain. I didn't help that the American at the meeting was a Soviet spy who wanted to destroy Britain.

And Bretton woods solved nothing at all, it was a system that took a very long to implment, much longer then people think and was unstable almost as soon as it was implemented.

The flow has definitely started reversing, and yep you're right there will be problems. Worldwide central bank holdings of gold just recently surpassed holdings of US Treasuries for the first time in 30 years. And I believe that's using only reported amounts of gold, when all experts agree that China has acquired far more gold in recent years than what's reported.