What would happen if the United States were to be completely destroyed?

Besides the obvious “we’d all be dead”, what would happen if, let’s say, an impossible amount of nuclear bombs were dropped on America, and our entire country was annihilated? As in, no survivors. Every building, landmark, etc is absolutely destroyed.

Obviously, this is an extremely unrealistic question. I was playing nation states, and chose to drop a nuclear bomb on a country. The country was incredibly small (It’s an online game), so the bomb completely destroyed the country.

If America were to be destroyed, would other countries celebrate?
Would our allies try to get back at the country that bombed us?
How would this affect other countries in general?