Pretty sure both Rex and Bonza will be mandated slots in the next round, that's if Bonza is up and running. The ACCC has already started to get involved so looks like VA and QF will have to relinquish some at some point, especially any unused slots held. Remember that slots are revisited on a yearly basis and redistributed on need, Covid had put a hold on normal redistribution as they chose not to change slot allocations until things settle down, which means next years slots will have to be assigned fairly to new entrants.
Have to remember that Rex was heavily involved in securing access for regional NSW routes into Sydney, they are very familiar with how the slot system works.