What we can with a little confidence still hope is that the world will retaliate only by blocking US exports, not with generic unilateral tariffs. Decoupling the US from the global economy would still be painful for both sides, but not nearly as painful as a complete meltdown. Unfortunately, the EU - which would be the key player after the US - does have a spotty record on free trade. It tends to prefer bilateral deals over global agreements, and fanatically defends its agriculture. Still, if it merely maintains status quo except for reacting to new US legislation, we should be OK.
I will also remind you that nearly 96% of the world's population lives outside the United States. What this world cares about is mostly America's money and guns. If those disappear from the world, you will not be very interesting anymore.
(*Ironically, Smoot and Hawley were both Republicans.)