Yeah, I agree with your summary AP, the A220 looks the obvious choice for replacing the B717 & F100 fleets.
.... except Qantas wont pay what Airbus can and are asking for them. Joyce basically said as much in the media release.
My money is on the 737 max (surely they will be giving them away for a while) complemented by Embraer (Boeing) for the 717. The F100s probably replaced with more high time 320s ex Jetstar.