In addition to what Wineglass said...
Currently the retirement age in HKG is 55. On the base in AUS it will be 65. The way the COS works is that once you reach 55 in HKG, you are forced to retire.
The only way to keep working past 55, is if you:
1. Become a check & trainer or
2. Take a base out of HKG or
3. Transfer to the freighter fleet.
So to make command slots worse in AUS, as all the senior guys get to 55, the bases will become flooded (assuming they want to keep working). As a junior member, I don't see there being much hope of getting a command slot on a base at all.