About FAA... If the previous "dual mandate" was formally rescinded or discontinued, it fooled me. Even a cursory browse through the FAA Authorization legislation reveals a large volume of projects Congress statutorily authorizes the agency to conduct, and which have a lot more to do with building up, or advancing, the overall NAS (National Airspace System) than with either certification of aircraft or other subjects essentially concerned with safety. The ICAO working paper is a spot-on illustration.
Privatizing the ATC function has been controversial, despite success of this move in other countries. Probably a big reason it hasn't happened in the U.S. is the need for Congressional appropriators to deliver, or at least to be seen as delivering, to their backers and donors. Call me cynical....
One other thing to be noted, IMHO. Faulting "politics" is a blind alley. Policy, and politics, and law, all go together to form the context. Sorry if it seems pedantic, but the existence and workings of civil aviation sectors, and nearly everything else, occur within a context built from all three of those central factors.