@amaroo -- there is currently a lawsuit in the US where one of United's "Million Miler" flyers has taken United to court, alleging that his lifetime MM status (somewhat equivalent to LTG) has been devalued by the airline, as they have added additional loyalty tiers above his, and his upgrades are not as frequent as they used to be. This could be one way for Qantas to manage its Lifetime Gold liability: just keep adding levels of loyalty to the top, and devalue Gold.
In Australia, Virgin already operate a points per dollar model on domestic tickets. I could be wrong, but I'm guessing Australia has far fewer opportunities for mileage running anyway (on Jetstar or Qantas, or accruing Virgin flights to partner airlines), as compared to the US, so such changes are less immediately relevant to us. YMMV