I would have thought Brisbanites would prefer going from MCY or OOL (noting that VA are starting OOL-DPS soon) than WTB - they are closer to where the population is.WTB-DPS could be a good one, scoop up Brisbanites and transfer in the others. If the fare was cheap enough I could imagine JQ customers driving up there.
Also, given that we're talking about JQ, doing MCY-DPS or OOL-DPS would be easier for JQ than WTB as they already have services from those two airports.