I'm not sure what your definition of centrally located is. Homebush is pretty much right in the middle of the Sydney metro area and is pretty well serviced by public transport from multiple directions with its own dedicated train line which operates on a direct line to the city for major events with a shuttle line from Lidcombe for people travelling from the west. The lower bowl was completely restyled after the Olympics and no longer fits an Olympic athletics setup inside it, even when in oval mode which hasn't been used in sometime and I've no idea if the equipment to set it up is still in working order. I have a pretty low opinion of the MCG as a viewing experience. Last time I went there was a while ago (when Mitchell Johnson terrorised the poms) and I had platinum seats in the Olympic stand and the seating was uncomfortable and cramped and you are a long way from the action. It's just a shit stadium all round and I would rather watch a game there on TV than haul myself to the ground. I've no problem attending games at AAMI Park. I've no idea why you think it wouldn't be used for any possible future Asian Cup. Optus stadium in Perth is much better than the MCG, but its still a cricket ground and provides poor views for football. I had about as good a seat as it offers on the front of the second tier on half way (section 345) and you were still a long way away. Adelaide Oval was comfortable enough but its still a cricket ground. From my seat on the lower bowl for the China match you couldn't see the ground from the advertising hoardings until close to the centre circle and I was closer to the back of the bowl than the front.The MCG (an Olympic stadium, centrally located and well served by public transport) is constantly used and often re-furbished. Stadium Australia (an Olympic Stadium but not centrally located and poorly served by public transport) has been used consistently since it was built 25 years ago.
It is true that some Olympic stadiums have had the fate you described but they were not centrally located and served well by public transport. In Australia we have not had that experience.
A Socceroo game against Brazil in Perth would sell out very quickly - only slowed by the ability of the ticketing system. An appropriately sized FIFA stadium, centrally located and served well by public transport is a gimme. While AAMI was use for the 2015 Asian cup it will not be for any future Asian Cup - it will just be too small and Brisbane, Perth and even Newcastle would make more sense financially.
Origin games are now more likely to go to Perth than Melbourne. The same with Rugby tests especially with the large amount of British descendents in WA.