I would be more concerned if PA's and NP's SOLE function was primary care, but they can just as easily subspecialize in ortho, gen surg, cardiothoracic, etc...
That's not to say I'd do primary care; in fact the PA/NP field is one reason I didn't do primary care. My father has been a PA for 20+ years, and from all I gathered form him (working in a rural ER setting), he performed ~85% of the tasks any MD would in the primary care setting. Cookbook medicine is cookbook medicine, whether you're an MD, DO or PA, and the 15% only comes into play when there's legal or really complicated issues involved. Sure, he has no where near the training & basic medicine background as your avg MD/DO grad, but that doesn't matter for a big bulk of stuff you see in primary care, especially after a few years experience.
FP has had their practice rights slowly whittled away over the years, as specialists (GI, OB, surg, etc...) have 'stolen' the business under the notion it's better to be taken care of by a specialist, and consequently have reduced the role of the FP to that of a glorified PA.
The AMA/AOA will fight tooth & nail the DNP (Doctor of Nurse Practitioner), et al, movements, but that's no guarantee, especially when politicians & the public really start to become worried about the escalating costs of healthcare...they may justify annexing even more FP practice rights & risking occasional knowledge-gap-based errors for cheaper costs, who knows.
On the other hand, some physicians really like the PA/NP fields...they can hire one, dump all the scut work/call on him/her, and increase their net income without having to pay the salary of a fully licensed physician.
In any case, it's hard to justify entering a field that an experienced PA can just as easily cover simply on the good-faith that our governing bodies & lobbies will maintain practice rights. Like I said, FPs RARELY perform all the procedures & tasks they historically have because those roles have been deemed more fitting to GI docs, OBs, gen surg, etc...and the malpractice is prohibitively expensive, so as an FP you're relegated to filling Rx's, physical exams, MINOR procedures, and your income is solely (usually) based on volume...ie: how many patients can you get through in a day?