I reckon some routes like Bundaberg to Melbourne and Sydney could work. Population 100k, only has two QLink flights a day to Brisbane.
Rockhampton has never really taken off. Tiger tried about three times, J* has pulled out from memory also. Bonza going in hard with 4 destinations. Rockhampton to Townsville sure is a strange one. I recall Tiger tried the Melbourne run, the Airbus was just too big however. Not sure why the MAX will fair any better.
I think you will find out of all the routes, the best performing one will be the one with competition. That being Melbourne to Sunny Coast. Question marks sit around the rest.