The FAA does not want to mingle with r/c as I know it, but they are stating that the AC-91.57 is outdated (1981). All of this would be for commercial uav's. They see the AMA as the governing body on r/c. The key is recreational use is slated to be AMA, commercial is what a "UAS" system is more commonly referred to, and would be commercial in nature. The bottom line is that they want safe integration of UAS into the national airspace.

Another link:
http://www.auvsi.org/news/index.cfm#News1697

Michael