If Iran gets to tax the strait of Hormuz, it's the entire world that will be doing the "FO" part. The EU, maybe China. For the US, consequences will be relatively minimal.

Obviously Iran will be using their newfound leverage to force policy changes in the EU first. That will be very, very bad.

(and if I can say something really unpopular: this is why Trump wants and asks for EU and other allies to support the US in this war. Not because it's just or fair ... nothing to do with it. More like "deal with Trump or deal with mullahs", expecting any sane person to choose Trump, rather than deal with the consequences of Iran either taxing Hormuz or acquiring nuclear weapons)