I found an article on how children’s working memory capacity predicts their school performance years later. It says:
In her latest research Alloway gave working memory and IQ tests to 98 children aged 4.3 to 5.7 years in full-time preschool education. Recently, six years on, she revisited the children, now aged 10 and 11, asking them to take a battery of tests to measure working memory and IQ. She said: “Critically, we find that working memory at the start of formal education is a more powerful predictor of subsequent academic success than IQ.” Alloway’s research is due to be published in the Journal of Experimental Child Psychology.
I find that interesting, but I suspect that predicting highschool and college performance will take more than testing working memory capacity. Good IQ tests involve executive function as much as working memory, and executive function influences abstract thought.