My hunch is on Alliance. They're taking care of business all over the place, and they're not taking prisoners.
That's because they bought a heap of older airframes when they were going really cheap so they're overheads are comparatively low and they have a large fleet ready to deploy at the drop of a hat. Buying a bunch of new jets would be fatal for Alliance and I don't think that is how they operate.
My guess (if they even are for an Oz operator) is the 717 replacement. The C Series has been talked about for many years as their successor. Which company will operate them? That is the fun question.
