It probably will not be an issue in Australia for the simple reason that there will not be many Avgas burning aircraft left flying.
CASA, Dick Smith, AsA and AOPA are making sure of that.
All joking aside look at all the trend lines for GA in Australia. Number of pilots, hours flown etc. The only healthy sector is run by the RAA.
CASA admit quietly that they want all paying passengers flying in turbine aircraft.