Good thread OP.
It looks like what a lot of us believe should happen is not so far fetched after all..
Notice the last paragraph...
From today's aero-news.net
Developing An Opt-Out Solution Based On Providing Operators An Alternate 24-Bit Icao (Mode S Transponder) Code
Given the long-standing recognition by government and industry of the need to maintain in-flight security, NBAA is working with the FAA and other stakeholders to identify the most effective means to ensure that operators continue to have the ability to opt out from having their flights tracked in real time, following a conversation many aircraft will make to new ADS-B technology, starting Jan. 1, 2020.
NBAA – through its involvement with the FAA’s Equip 2020 working group, as well as engagement with the FAA’s Surveillance and Broadcast Services, System Wide Information Management and System Operations Services groups – is working with the agency and other general aviation associations to develop an opt-out solution, based on providing operators an alternate 24-bit ICAO (Mode S transponder) code.
Under this solution, operators would retain their permanent transponder code tied to an aircraft’s N-number, but would also be able to use a secondary, non-published code, assigned and managed by the FAA, which would not link to the specific aircraft tail number. It is expected that operators could request a new secondary code at least once every 30 days.
The addition of this new, secondary ICAO code program to the existing FAA Blocked Aircraft Registration Request (BARR) program would address not only what information managed by FAA is shared under BARR, but also the data transmitted by the aircraft itself to determine its identification throughout the NAS. While private ADS-B receivers could still detect an aircraft flying overhead, they would not see any information allowing them to match that aircraft to the owner listed in the FAA Registry.
“Everyone agrees that a person shouldn’t need to give up his or her security when boarding an airplane,” said NBAA president and CEO Ed Bolen. “We remain committed to working with the FAA and others to ensure that operators are given an ability to opt out from having their flights tracked in real time, basically by anyone, anywhere in the world, who happens to have the appropriate equipment for doing so, and whose intentions may be unknown.”
Since 2000, Congress has repeatedly passed legislation mandating that the FAA provide a means for opting out from real-time flight tracking, regardless of the technology involved. While such a provision has long been in effect in the U.S., it does not necessarily apply to international flights.