Truth is, FPs are not paid much more than PAs.
FP salary 100-140K starting
PA salary 60-90K starting
As for replacing FPs, that's true and not true. Yes, if you hire more PAs, you don't have to hire as many FP/IM/Peds/etc. However, a PA must work for an Dr., so there has to be a Dr. around somewhere.
My wife goes to a NP for her primary care, and she really likes her NP. However, if she had a serious medical problem, she'd go to a specialist. This is the way it's changing.
BTW, it's totally different in rural areas, South, Midwest, etc. They don't accept PA/NPs as much, they want their doctors, and they pay pretty well.
Some FPs make serious bucks and do lots of interesting things from Dermatology to Surgery when there aren't a lot of specialists around.
From the little I understand, I would only do FP if I planned to live outside of the city, or if I was totally committed to family medicine.
They have 'primary care' IM tracks now, which are a little bit FP but also allow you to do the hardcore specialities of IM if you want. Also IM/Peds is only 4 years.
Luck,
ERIC