The simplest answer is the jets were coming. After maybe 7 years of evidence on how much delay there was in starting modern aircraft manufacturing it was obvious any new design would not be in service in numbers until the later 1940's, which means jet to be competitive.
The post war RAAF was going to be small. After 6 years of war the government had a lot of debt to clear while the air force had few possible enemies and a lot of modern piston engines types with few hours on them, backed by lots of spares. The P-51 in 1945 was costing around $50,000 each, in 1949 the F-86 around $250,000, some if that is inflation, much of it is the rising complexity, the smaller production runs and the greater precision of build needed. As the jets entered service and pushed to supersonic speeds there was about as many advances in maximum performance in the second half of the 1940's as the first.
The Australian built replacements became the Vampire (September 1949), Canberra (July 1953) and later again the Avon Sabre. Mosquito finished June 1948, Mustang and Lincoln in July 1941 (apart from 1 Mustang officially in April 1952).
The US was not exporting its latest designs post war, which is why so many countries flew Vampires and Meteors. The P-82B acceptances started in October 1945, as of July 1945 only 20 were on order, dating from the June 1943 J program, the July 1945 L program did add another 250, even so it was not going to be a major fighter and was meant as a long range escort, not fighter bomber.
Commonwealth Aircraft Corporation Fishermens Bend work force peaked at 7,400 in mid January 1944, dropped off to slightly over 4,800 by end 1944, rebuilt to 5,500 in July 1945, North American Aviation employment figures were around 83,000 and 37,000, the bigger you are the more experiments you can support, like armament and design changes with associated retooling. CAC was heavily reliant on imported machine tools, North American had local supply.
CA-15, competing to an extent with the CA-14 bomber project until its cancellation in mid 1944.
R-2800 engine received in May 1943. Initial design engine P&W R-2800-10W, after May 1944 became R-2800-57, after August 1944 became Griffon in line, engine changes forced by lack of supply, entire project suspended September to December 1944 until a decision by the war cabinet to allocate a limited budget, taxy trials February 1946, first flight 4 March 1946. Like types such as the MB-5 it had advantages over the types in production and years before it could be around in numbers, but jet designs were already in production.
Even if the Pacific War had continued into 1946 the RAAF would have received the Beaufighter, Mustang, Mosquito and Lincoln, probably retiring the various operational types it had in small numbers. Highly unlikely new local production lines would have been authorised, as by 1945 the allies had a surplus of aircraft.