They rebooked me on the next morning's JQd flight, MEL - ADL, they said (if I remember correctly), I could claim from them for the hotel fees for overnight.
But MEL airport only has 2 hotels either the Parkroyal ($$$) or the Ibis Budget.
But I had to start work very early the next morning, so couldn't accept it.
Had tried OLCI the night before the flight, 23.5 hrs before, but not available, the message said, tried the kiosk 2 hrs prior at MEL T4, not available, it said, but no mention of cancellation.
Come back later, the staff said, I didn't know any better.
So I went to the T1 QP, for which I was a member at that time.
In the lounge, got an sms that my JQd flight was cancelled.
Couldn't accept the offer to get next days first JQd flight.
So, went to QF airport sales and bought a flexY tix, in the end, got QFF points and QF SC for both the JQd cancelled flight, and also the QFd flight I took.
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If they do cancel, it would be put onto the next days flight, most likely.
Take a look at www(.)flight aware/radar to see how many cancellations there were, for the last flight from ADL.
Unlikely they would put you onto QF, as dep on where you are flying to, JQ can be the last absolute flight out of ADL, eg, ADL - DRW, absolute last flight of the night, most nights.