I don't think the US going 1st->4th is at all meaningful. According to the report the US went from 2nd to 18th in "adaptive attitudes" and 2nd->8th in general "

I don't think the US going 1st->4th is at all meaningful. According to the report the US went from 2nd to 18th in "adaptive attitudes" and 2nd->8th in general "future readiness." This seems more like a difference in how IMD is measuring things than a change in US economy/policy. But maybe the EU did something that moved their rankings upwards? In general there is too much complexity behind the ranking to tell a meaningful story about such a small decline in said rankings, especially when none of the variables are particularly quantitative in the first place! It's better to interpret this more as "the US is consistently in the top 5" than "the US is slipping," or "those wily Singaporeans finally beat the Americans."