Qantas will need to act quickly, especially if DJ deploys the E-Jets on the Q400 routes (SYD-CBR, BNE-CBR, BNE-ROK, BNE-MKY, BNE-GLD and BNE-EMD). Up until a few years ago more than half of the above routes were operated by jets (NJS with the 146 and FWA with the F28/100).
As topgun007 said, Qantas could get put the B717’s back on these routes or make use of the 146 again (short term) or have Skywest and/or Alliance operate their Fokker’s on behalf of Qantas.
If there’s a jet and a turboprop operating the same route, Joe public will always go for the jet (no matter how old it is).