If you don't continue to make payments on your Australian credit card, the consequences could include:
Additional fees and interest on your Australian credit card, increasing the total amount of your debt.
Late payment or default listings on your Australian credit report. This may make it harder for you to obtain credit if you return to Australia in the future.
Your credit card debt may be passed on to debt collectors. While most debt collectors in Australia operate nationally, there are some international debt collectors that could attempt to recover the debt when you live overseas.
The credit card provider may take legal action, which could include suing you for the amount owed or having you declared bankrupt.