I think the problem is that there is no incentive to drive Medical Students towards the PCP life. Although there is a Rural Medicine program, giving more incentives in the form of loan forgiveness might begin to drive students towards that route. I know that one reason I was turned off from being a general Pediatrician (other than that I'm learning to loathe Embryology and Congenital defects) is that after staffing, building maintenance, malpractice insurance, mortgage, car insurance, food, electricity, water, and family maintenance, there just is not a lot of money left over to pay your loans back in a timely period.
We could get into the breakdown of medical school loans, but I think that it is a little bit beyond the scope of our discussion. Simply put, giving medical students who enter primary care some kind of loan forgiveness (20%, 30%, 40%, or more, depending on location and need in that area) would draw more students to that lifestyle.
I cannot comment too much more, as I am only just beginning my medical school career. I have heard from people in the outside world that our President Elect has been tossing a similar idea around, but I have neither the time nor the energy to do anything but study, sleep, and, occasionally, drink.
Good luck.