I don’t believe there is any federal authority over the AMA (American Medical Association). Its a private organization. So the FedGov can’t abolish it. What states could do is stop letting the AMA tell them how many can be admitted to state medical schools.
Nurses, nurse practitioners, and physician assistants can do the same diagnosing and routine/general treatment that a doctor can. And they can establish practices in rural or inner-city areas that don't have them.
The AMA is to healthcare what the FDA is to drugs.