I expect that tort reform will probably rein in the insane malpractice fees a lot of specialties are suffering under. It may take a shortage of Ob/Gyns before law makers are willing to take those measures, but the day will come. Managed Care was worse in the mid-nineties. The backlash over the past decade or so has resulted in a trend toward PPOs and consumer directed healthcare, which make it easier for physicians to practice. Doctors will probably continue to be highly paid if they're specialits, though there will probably be a redistribution of income. Cardiothoracic surgery is on its way out as interventional cardiologists encroach on their turf with ambulatory procedures. Geriatrics, orthopedics, and other specialties that deal with old people will gain demand as the baby boomers continue to gray. I guess that prospects are slimmest for primary care docs. Their turf is being slowly taken over by Physician Assistants and Nurse practitioners. Furthermore, they tend to be salaried and thus make less than specialists that are paid per procedure. IMHO, I think more and more preventive/primary care will be left to allied professions and MDs will end up being mostly subspecialists (actually, most are already) In the next decade or so, the number of med school seats will increase substantially. However, even though this may seem like increased supply, it may not drive down salaries. A lot of physicians are foreign docs (~25% I think). As US Med school grads increase, I believe it will be harder for foreign docs and carribean grads to gain residency positions.
All in all, I don't think there's need to worry. If you have an MD you have a real "skill" that is absolutely essential.
Just my 2 cents. I don't know jack squat about any of this.