I don't think "RAA" would ever be able to issue RPL's, however they could operate like a Part 141 organisation and have examiners who are able to issue licensing under CASA. It would mean RAA CFI's would need CASA instructor privileges of some kind. While I doubt this would come about quickly, in my opinion it would be a logical step for RAA to pursue. Focus more on aircraft registration and less on the licensing.
2 Main hurdles:
Getting CASA onboard to reduce the medical requirement of the RPL inline with what is required now for RAA - Ie Medical declaration, with similar restrictions (1 pax, VFR 10,000 ft or below, no CTA). These restrictions could be lifted for Class 2 Medical Holders.
Insuring current Instructors (RAA) can continue to operate under the CASA system without undue costs (Having to gain CPL, Class 1 Medical, Registered as Part 141 flight school etc)
Aircraft would still be operated under CAO (minus the RPC requirement), pilots would need need to be RAA members and operate according to the Ops Manual (in RAA registered aircraft).