The FAA just took the next step on their inexorable push toward the NextGen air traffic control system. The latest development is that they've mandated ADS-B Out equipage for most types of airspace by 2020. (See Avweb for the article.)
When i say 'most types of airspace,' I mean those in which a Mode C transponder is currently required. Class A, B, C, E above 10,000 ft and a couple others. In a way, it seems like this can't be too bad. I'm sure there was push-back when the FAA started requiring Mode C transponders even though they significantly increased safety.
However, I'm still not convinced that ADS-B represents such a significant increase in safety or anything else good for General Aviation in America.