It's the economy.
Dropping pay to 70k would implicate that:
1.) cost of living has dropped
2.) costs associated with practice have dropped
3.) The invisible hand is at work. Extreme healthcare reform.
Now we have extreme left democrats out there yelling doctors should never make more than 90k a year. Those are extremists. So practically if it did get dropped by some healthcare reform, I would expect it to be less drastic than to 70k. Also, I would think that the healthcare reform would, at the same time, reduce the paperwork load on said physicians, thus reducing the amount of hours required to work while reducing the pay.
That being said, if it were 70k, I would still become a doctor. 70k is enough to gradually pay off debt and still live comfortably. I'm not particularly materialistic, just want a reliable car, a well furnished apartment/house, decent clothes, and to eat well. I think most single people can do that on 70k a year. Most importantly, I'd be earning it doing something I enjoy. I would take 70k to be a doctor over 150k to be a lawyer. Any day of the week.