In a nutshell, foreigners and empirical work:
This short paper collects and studies the CVs of 112 assistant professors in the top-ten American departments of economics. The paper treats these as a glimpse of the future. We find evidence of a strong brain drain. We find also a predominance of empirical work.
Three-quarters of the bachelor degrees were obtained from abroad. Macro, econometrics, and labor economics are the most popular fields, see p.8 for the full list. Here is the paper, hat tip to Pluralist Economics Review.