IQ is one of the greatest corollaries to success, and from the research I've seen it's unlikely to change dramatically from age 8 till death. This is a topic I rarely see discussed.
A lot of people like to mention Gates, Jobs and Zuckerberg as examples of college dropout success, but fail to notice that those who succeed to a great degree all possess very high levels of intelligence. Gates, 1590 SAT. Zuckerberg, 1590 SAT. Kalanick, 1580 SAT (dropped out). Drew Houston, 1600 SAT. Read Patrick Collison's bio, https://en.wikipedia.org/wiki/Patrick_Collison.