If you're feeling a bit adventuresome, the overland borders are probably still open, so you can go to Kyrgyzstan, and from there fly to IST for example. You can even go overland farther to China, but you may not be able to obtain visa to enter.
Kyrgystan is not allowing foreigners to enter the country, all of Central Asia is locking down.
It looks like Uzbek Air will run a flight on Saturday to Delhi, where it looks like we can transfer to Singapore Air and get to Brisbane via SIN.
The other possibility is a charter to Tokyo on March 31, April 1 or April 2 which I guess will be Plan B if the Delhi flight doesn't work out, but it will probably be harder to get flights back to Australia by then.
Any thoughts/advice welcome.