In one, Howabout
Leadsled, I know exactly the argument your CSIRO mate would have used. After changing the quadrantal heights to hemispherical heights with IFR on 1000's and VFR on 500's there is a situation where you can have near collision course from 180deg opposite directions, where quadrantly, opposing traffic was always from your quarter so always posed a profile...easier to see.
And why did the hemispherical come in? Not because of ICAO alone..Oh no, it was because VFR no longer was under FPR so we had to separate IFR from VFR so the two would never meet...shame about the head on stuff.
Howabout, it would be so simple to impliment. ADS-B is now 100% of airspace ABV FL300 and huge amounts A010. Regional towered aerodromes with an ADS-B receiver and a feed, complete with an en-route qualed FSO to look after the airspace from the bottom of C/A to the terminal area.
I just hope those guys from the CASA are still paying attention to these threads. Guys, have a study of Flight Services and see the synergy that could apply with ADS-B equippage.
If you do, you will see that the wheel is about to turn all the way around to the exact same track. Excepting, if the dillitants had kept out of it, evolution would have done the same thing without the millions wasted on a silly experiment.
Some hints, remote VHF outlets, Virtual TAAATS tracks, basing in ML BN SY and PH. Maybe at the new towered aerodromes. Virtual tracks replaced by ADS-B derived "real" tracks. Once tracks are real, dropping of the need for FPR. FSOs rated up to en-route standard. Career progression due to TAAATS experience, elimination of the dreaded TIBA. It's all in place and could have easily progressed from the eighties right to now without AIRSPACE2000 the NASdebate and the outright decimation of a very experienced workforce that could esily adapt. All it would have took was a couple of unions to kiss and make up.