There are easier ways to make money and not take on that much schooling and debt. By the time you get done the gov't could be dictating you salary as a doctor.
To me the healthcare market is the one that is at the most risk right now.
You best bet is to look at the forbes 400 list and see what industry is most prevalent and among the most wealthy.
another track would be to look at where the most public dollars are being, or will be spent in the private sector. Environmental science, farming, etc.
You can also make a lot of money is sales or as a property owner. Shit, I barely graduated college and sales is treating me better than if I would have spent a ton more time and money in school to become a doctor. Certainl not as rewarding but it pay well.