Frey has calculated that if the U.S. does not improve its college completion rates for young people, the share of Americans holding at least a four-year degree will start to decline as soon as 2020. After that, his model forecasts that the share of college-educated Americans will not climb back to its level in 2015 (just under one-third) at least through 2050.

That’s an almost unprecedented prospect for the American economy: The percentage of Americans holding at least a four-year degree has increased steadily since at least 1940, according to the Census Bureau. It’s also an ominous prospect in an international economic competition increasingly centered on knowledge and innovation.

The reason the U.S. faces the risk of declining educational achievement is its failure to sufficiently respond to the profound demographic change reshaping society. The current school year marks the first time in American history when a majority of all K-12 public school students nationwide are minorities. Minority students already comprise nearly two-fifths of high-school graduates and will reach about half by 2023, the Education Department projects.