If presented with a false choice between Idiocracy and the Terminator, I'll take Idiocracy. I'll bet that the people who choose the Terminator have no children.

You seem to have become, like, totally Malthusian since reading Turchin, so I wonder if you had the same reaction to this as I did: 
 
>As documented in Benjamin Friedman's The Moral Consequences of Economic Growth the norms which we might define as broadly liberal individualism seem contingent upon a regime where one perceives that the future will be characterized by greater prosperity than the present. 
 
If you believe that, and you believe in limits to growth, that means that liberalism is a phenomenon limited to the steep part of the sigmoid curve that's doomed in the long run. Looking at the blurb for Friedman's book at Amazon, he wants exponential growth forever to make the world safe for liberalism, but whether that's possible is questionable.

tggp, Mearsheimer said that Germany would get in a nuclear arms race if the superpowers went home. That hasn't happened. We're still there. He was still saying in 2004 that there will be an arms race in Europe if America goes home: mearsheimer.uchicago.edu/pdfs/A0039.pdf

I'm mostly ignorant of Islamic history, but I have to wonder how much the size Muslim rentier class grew during the time in question. They would have been rich, extracting that jizya from a large population of dhimmis, and if they were anything like modern-day oil rich Saudis, that would have meant tremendous population growth which would really add up over several centuries.

Well, it makes sense. When it becomes possible to make designer babies, everybody will be forced to make them, or their children will be left in the dust. It'll be like the rise of agriculture or the industrial revolution - participation will not be optional in any realistic sense. So naturally, people who don't want to go along with it would be smart to crush it for as long as they can. 
 
Here's an interesting article which explores possible consequences of the ability to engineer ourselves in a deeper way than the one linked above: 
http://www.nickbostrom.com/fut/evolution.html

No, he didn't, but that really doesn't matter. That's not the main reason why "SSBBW" is becoming a recognizable acronym and we're not eating 1200 calories/day. The demographic transition is. 
 
Malthus claimed, based on the behavior of Americans, that human populations doubled every 25 years in the presence of abundant food. So here's his projection of what would happen if world food supplies could be increased at the rate of X every 25 years, where X is the amount of food produced in his time: 
 
"...supposing the present population equal to a thousand millions, the human species would increase as the numbers, 1, 2, 4, 8, 16, 32, 64, 128, 256, and subsistence as 1, 2, 3, 4, 5, 6, 7, 8, 9. In two centuries the population would be to the means of subsistence as 256 to 9 ; in three centuries as 4096 to 13, and in two thousand years the difference would be almost incalculable." 
 
Projected food supplies now would be about what they actually are. Granted, this was a reduction to the absurd, and he didn't believe that we could really achieve this, but the point was that even if we could, it wouldn't keep up with projected population growth. Human ingenuity was almost irrelevant to his theory.  
 
Most of us would be near starvation, and nobody would know what "SSBBW" stood for, because there wouldn't be any, outside of some very rich families who would still use corpulence as a status marker. We would need some serious sci-fi tech to feed 100+ billion people, which is where we'd be now, and far more human ingenuity than we've shown. 
 
But population growth didn't come close to keeping up with his projection, and it points to the real weak spot in his theory. Yet hardly anybody talks about the great importance of family planning, at least not compared to the relative hordes of libertarian Julian Simon fans who'd rather talk about GM crops. 
 
I know this has little to do with the real point of your post. Just a pet peeve of mine.

There's a lot of nonsense out there about Malthus. He did not fail to account for human ingenuity - if he had, he would have said that food supplies remain constant with time, when in fact he said that they rise arithmetically. You guys are thinking of Paul Ehrlich.

Consider the possibility that babies could be raised outside of the womb from day one. In that case, people might well breed congenital addicts for money. The parent/s wouldn't necessarily have to raise the child his/her/themselves, and a lifelong addict would probably be worth enough for the seller of the addictive substance to pay to raise the child. If there were no costs to the parents, surely you could find somebody to do it.  
 
With cloning, you wouldn't even need parents as we know them.

What's the deal with the secular people of Islamic heritage? Do they tend to be assimilated Frenchmen, or do they burn cars?

As others have said, medical careers are excellent choices. The path to becoming a nurse is relatively short and lucrative, and pharmacy (my career path), dentistry, optometry, and podiatry all pay quite well too. 
 
Assuming that dentistry is roughly equivalent to pharmacy, I disagree with chairmanK that it's unsuitable for people with IQs below the 95th percentile. The coursework is not so difficult that you couldn't make up for an unremarkable IQ with hard work, unlike, say, mathematics or physics, which would be impossible for somebody of modest talents. Most biology courses are just about memorizing facts and regurgitating them for exams. Intelligence is helpful, but optional. 
 
But if you're both lazy and not that bright, forget it.