I think you misunderstand. I'm not arguing that the US will face a shortfall. The data above show that the US imports less than 25% of its bromine, but are redacted to prevent the public knowing the real amount. Factories in America are unlikely to face shortfalls of bromine.

But unless we have an extra 250 million tonnes of production capacity sitting on the sidelines, which would probably mean more than doubling our total output, we're not going to make up the shortfall for anyone else. We're talking about the majority of (disclosed) global production going offline if Iran could manage it (though again it is not clear that they can or will). China will also probably be using everything that they produce. Europe and the rest of Asia will be left high and dry. It's a win for the US strategy of critical minerals resilience, in some sense, but it's still a problem.