DPO has been a very strong airport for a number of years with QF being very happy, council has never owned was always the port corp. they were looking at selling it as it was not core business but the local consortium were only offering peanuts so the state Port Corp is now spending 5 million on the terminal in readiness for security and at the same time are doing a lot more already starting to look good.
DJ may well do OK in Mildura if they can increase frequency.
The regulars out of DPO are getting quite used to the Q400 which does around 2 thirds of the flights out of DPO appreciate the extra speed compared to the older Dashes
MEL NTL was a long haul for a old dash but the Q400 would handle it well, problem is you are competing against A320's and E190's.
Putting some Q400's (or ATR's but I don't rate the confort level) on some longer routes such as DPO SYD have a lot of potential