Doubt it would work now for QF, since they are stopping at DXB on the way to LHR.
When hobbing through SIN, it could have worked, in that there were flights arriving from BNE, ADL, PER, DRW, to connect onwards to CDG, LHR, FRA, but not now, can't see a CBR-DXB being put on, and I doubt CBR-SIN would last as a purely O&D route.
SQ on the other hand would have the advantage of feeding into a much larger network, northern Asia, Middle East, Europe and Africa, all of which would involve one, maybe two, transfers if flying out of CBR (more about that later). SQ would be able to turn these into much more attractive trips, with the first transit being at SIN (worse airports to transit through) rather than SYD or MEL.
IMO this should be a real winner for Canberra and anyone who dislikes the prospect of a drive to SYD on the Hume Hwy.
And even those who dislike the transit process at SYD as well!
Dave