From what I know they can still be paid their support money by Swimming Australia and attend universities over there on athletic scholarships. The scholarships in the US are worth a ridiculous amount - upwards of US$50,000 and that was from my experience back in the early 2000s. They include all university fees, on campus accommodation and food, all training, and medical and a small allowance. I believe they can still get medal and performance bonuses from the government, etc too.
Sponsorship by someone such as Nike would void collegiate eligibility.