Playing the Devils' advocate; why should the IFR aircraft that are being talked about not be equipped with ADSB? Yes, Australia is unique in the world with the requirement but it is a bloody unique bit of real estate. Can you show me other places with such huge tracts of land, other than the USA, where radar can cover the areas concerned? The Americans have spent huge amounts of money on the infrastructure to date and if you're expecting Australia to do the same, who is going to pay? ADSB is very cheap compared to radar coverage and I'm sure that if the USA was in the same situation as Oz they wouldn't go to that expense now when there is a much cheaper alternative. Why should the airlines, military and top end IFR have to fund providing a radar infrastructure that they don't need to just because the minority don't want to pay out on new kit for their aircraft?
If you're not prepared to pay for the service you want then you're going to have to go VFR because it is entirely unreasonable to expect the tax payer (Government funding and military funding) and airline passengers (airline contributions) to fund the infrastructure enjoyed by relatively few people.
Nobody ever told us flying was going to be cheap but if you want the certified equipment necessary for the IFR service you want then you're going to have to dip into your pocket.
And please, enough of the histrionics. Painting a picture of scud running aircraft crashing in droves because they've been forced out of IFR is disingenuous and does little for your argument. Given the benign weather we enjoy in Oz there is already little enough scud running taking place. The increase in the amount because a few people don't want to equip with ADSB is so negligible as to answer 'no' to your question and will tend towards zero as those that do have their flying curtailed as a result of their stupidity.