ZDNet reports that Victoria is going to test native MIFARE based Mobile Myki on Android devices before rolling out the service in 2019. It sounds like a good plan, staying with an established closed ticketing smartcard system on mobile is the smart way to go.
Unfortunately Sydney is not making the smart choice, they are looking to dump their MIFARE based Opal smartcard system built by Cubic and replace it with ‘open’ EMV contactless:
While Melbourne is headed down a path that replaces physical cards with smartphone apps, Sydney is examining the prospect of dropping transit cards in favour of credit card usage.
In July, Transport for NSW began a trial on the Manly Ferry of using MasterCard instead of the Opal card for ticketing, allowing for mobile devices or wearables equipped with NFC payments connected to a MasterCard account to be used.