Looks like a membership is required to read the full article, so I can only speak of your brief synopsis.
Based on that, I have a notion regarding his theory. There won't be 100 economists. If Uh-merica started giving free college education to all of it's citizens, the numbers wouldn't change that much. plenty of people would still opt to work at McDonalds, deal drugs, be a rock star or pimp hos. Plenty more would go to college to get drunk, laid and expelled. Like Judge Smails said, the world needs ditch-diggers, too. I suspect you'd see a small increase in people going to college that otherwise wouldn't, but not much. Of that small group, plenty of them can turn out to be people with something genuinely good to offer, that otherwise would have gotten left behind.
I really don't know how anyone could argue with pragmatism like this.
Though, I'd add I don't think it's so much a choice, as much as it is that anyone who actually
wants to become an economist, is probably going to be able to at least find scholarships, etc, so that they'll most likely be going to college. There'd be a few who simply couldn't afford it and be left out in such a system, but I doubt it'd be a terribly large incentive.
And as for his actual solution, I'd say America sorta does something similar to that as it is. Without knowing more, I'd say perhaps if loans aren't involved - with loans involve, students just end up having to take out large loans, that they most likely don't full understand the consequences of, and which they are more or less forced into by societal pressure to get a job, and get an education. I can't find the statistics right now, but younger people are being especially hurt doing the recent recession/depression in America (something like 55% of people under 30 don't have a job, and they also generally are around ~20k in debt, with a net worth of around 3k... which describes me to a degree). I think there's a lot to be said for a voucher system, it's not a new idea in the world, but I think in the end, you sorta have to set a limit for what you will subsidize - that is, only subsidize if it covers like 80%+ of the cost, or some other percentage, cause I just pulled that out of my ass.