I am also a pre-med but I will offer my input.
The ACA is going to be a negative force on physicians' income, no question about it. However, this may not be as bad as some may portray, especially here on SDN. Under "Obamacare", physicians may need to work harder to maintain their current compensation. I genuinely believe that there is a limit to how low the government can reduce physician's salaries without the risk of losing the brightest minds in medicine. With the current cost of medical education (money and time), few will accept to work for less than 200K. I, for one, would prefer to relocate to Canada, Australia or even the Middle East.
Also, ACA will create an enormous shortage for physicians in pretty much every field of medicine. Midlevels will be given a broader scope of autonomy to meet the demand. Although many believe, and propagate their believe, that these midlevels (CRNA's, NP's, and PA's) are threat to physicians. I disagree. Yes, many midlevels have been pushing for full autonomy and equal pay, but that does not mean that they will compete with physicians for same jobs. Anesthesiologists are the kings of anesthesia and they are the main providers; CRNA's are only alternatives and will always remain this way.
Bottom line, I think doctors, especially anesthesiologists, are irreplaceable. They will continue to thrive regardless of politics. Midlevels will never pose a threat to competent physicians; they only overcrowd themselves.