The chances are that the new owners have negotaiated a deal based on “vacant possession” – even if they intended to rent the place out. Everything is so much clearer then.
Your best bet is to get in touch with them and tell them that you would like to continue the tenancy when they take over ownership but would prefer to know now if that isn’t in their plan.
This would be a brand new lease and would have nothing to do with the current owner.
The only way the current owner would be able to negotiate your lease into the future, after they have sold the property, would be if it was part of the sales contract (and it won’t be, trust me).
If you had been in the middle of your lease when the sale went through and the landlord hadn’t told you he was planning to sell when he signed your lease, you would only have to give 14 days notice if you found another place now.
But it sounds like your lease will end when the new owners take possession. Even so, don’t wait too long before you start looking for somewhere else to live.
You can find out more about your rights by logging on to http://www.tenants.org.au.