Achievement Gap and National GDP: Fantasy or Fact?

This recent NY Times article reports on a study that argues:

[If US] achievement gaps [of poor and minority students] were closed, the yearly gross domestic product of the United States would be trillions of dollars higher, or $3 billion to $5 billion more per day.

Looking at the actual study, however, it seems as if they are assuming a linear relationship between increase in education and increase in employment.

(See page 84 and 92 of their supporting documents. In their charts starting on page 88, they state that the outcomes they assume are "determined by assumptions about the ability to make use of higher skilled people and the quality of economic institutions.")

As I noted earlier, there is a great deal of evidence that education does not create jobs. In other words, these increases may happen on the margins, for the first few kids, but will fall off drastically after that.

I'd be interested in other perspectives. But it seems to me like this report simply feeds the fantasy of schooling, that if we just made schools better, all of our economic (and then social) problems would be solved.