Creamie,
M'learned friend, a question for you.
ICAO has no plans to mandate any or all of the three competing ADS-B systems.
In the absence of such an ICAO mandate, can the Commonwealth of Australia ban non-Australian aircraft from Australian airspace, contrary to the provisions of the freedoms established by the Chicago Convention, if they do not carry a form of ADS-B that meets the proposed Australian mandate.
Put another way, does the Australian Constitution give the Australian Government the power to make such a rule that is enforceable on non-Australian aircraft.
Tootle pip!!