Throughout the ACA conversation, it has been said that little was included to expand the supply of doctors that would meet the needs of the newly insured. This article suggests that the demand for additional doctors is not mainly driven by the ACA, but instead by an aging population:

http://www.washingtonpost.com/blogs/wonkblog/wp/2012/11/16/maybe-obamacare-isnt-driving-the-doctor-shortage/