Under current draft legislation Australians who are considered to be non-resident for purposes face important choices in regards to existing property held in Australia. Under the new legislation any property purchased after 19th September 1985 changes to CGT ( capital gains tax) removing the main residence 50% CGT discount if you sell the house before returning to Australia. At this stage it appears that if you return and live in the house for 3 years then the main residence discount will apply.
Simply working overseas does not in itself make you non-resident. You need to be away for two years and establish a home overseas.
It is as yet unclear how things will pan out but important that you get some good tax advice before making any decisions.