The issue in the article isn't that there will be novice programmers or lawyers, it's that if you can even become a novice programmer or lawyer, you're supposedly already in "Extremistan". The premise is well-contained in the quote early on that "most people are like horses" and can't operate in fields that require primarily intellectual labor.

I'm not sure that I agree with this premise, but it means that it's not an issue of crowding out newbies, just an expression of the popular sentiment that "[insert highly-paid professional position here] are really, really smart" and that to even attempt to become a highly-paid professional x is out of the reach of most people.