yes that is true, but you can be pretty sure that this will not be the case for many fields. I remember reading an article two years ago in NEJM by the director of the neurosurgery res. program at NYU. The article was a piece about the past, present and future of training in the field. This guy was overtly pessimistic about the future of neurosurgery residency programs, forecasting the closing of programs, decrease in funding, decrease in training spots.
I think that the surgical fields will be hit very hard. I think that other fields like optho, anesthesiology, radiology, and primary care will be hurt b/c of non-physician providers.
I think that fields that older populations seek in disproportionate amounts like cardiology, neurology, pm&r, geriatrics, etc. will see an increase in demand.
EM will also increase in my opinion as society continues to become more violent and more and more uninsured go to EDs as their only access to health care.
A word about the money. Let us not forget that the elderly, in general, use medicare. Note that at the present day, a very very large percentage of GME funding is derived from this same source. Withdrawing GME funding in order to pay for health care funding of the "baby boomer" generation is an option that is being taken quite seriously in congress these days. If that happens, expect to see a decrease in many specialty field training slots.
So on one hand, baby boomers will use more health care (ie require more doctors, or at least health care hours). On the other hand the increase in baby boomers may lead to a decrease in the number of doctors trained.
Too bad no one can get in together and restrict the number of people entering medical school. Rather the case is likely to be that in the future some med school grads will be unable to obtain GME training and, ergo, licensure.