Folks,
Re. Various comments about "over the Pacific", what you are referring to is FANS-1 and successors, which has been around for about 25 years, nothing to do with ADS-B.
Re. Alaska, the system originally installed in Alaska is the UAT version of ADS-B (much cheaper, and available throughout US) and not the seriously technologically challenged 1090ES adopted for all here, and adopted for larger aircraft ICAO wise. A very unmeritorious decision that was not based on technical superiority and forward requirements, but political lobbying by cash strapped airlines, and not only did it/does it not turn out cheaper, as advertised, but many times more expensive than fitting stand-alone UAT.
Re. The extent of the Australian mandate, even EASA-land will not require anything like the Australian mandate.
Just recently, face to face, the architect of ABS-B in Australia told me that the Australian mandate wasn't really any different to the US --- I wonder if he really believes that --- because he knows damned well that I am across, in detail, what the FAA requires.
What FAA does in the long run will be "interesting", based on the current rate of fitting of ADS-B to the US fleet, and the available resources -- including manufacturing the bits and pieces in the first place, there is no practical chance of the fleet (particularly airlines) making the deadline.
Tootle pip!!