Why do you think intellect would not be rewarded under a closed American free market? There would still be higher paying physician, engineer, and management jobs.
In fact, did you know that under our current system, intellect is often NOT rewarded but punished? Every time someone graduates from college and cannot find a job in his field yet has student loans that can't be discharged in bankruptcy, as is the case today, intellect is punished. We have large oversupplies of PhD. scientists, MBAs, and lawyers (all high intellect types) who are unemployed and underemployed.
Since intellect is currently being punished in this country, what makes you think it would be even more punished if we had trade protectionism and greater government regulation of the amount of people who go to college?