It seems Australia got itself into a bit of a pickle.
I'd say the problem began in 1998 when Australia began the HUG program. Instead of upgrading the classic hornets, they should have bought two squadrons of Super Hornets. If the classic hornets were not upgraded then there would have been little reason to start the CBR program. By upgrading the classic hornets its forced us to rebarrel the aircraft as they are now quite modern in terms of their avionics.
A good way to put it would be placing a brand new 2005 model engine into an old 1984 car. If the car then developped rust you'd be forced to repair it due to the value and performance of the engine. Putting the engine into the 1984 model car may have seemed good value at the time. However once taking into account the cost of the rust repairs it would have been better to just buy a 2005 model car that came with the engine you wanted.
If the CBR, APG-73 radar and system upgrades cost for example 5 billion for 50 clasic hornets, and that 50 brand new superhornets cost 10 billion for 50 aircraft, then to see which one is better is fairly simple. If the classic hornets had 50% of their life left while the superhornets would have 100% of their life left then you are getting twice as many flight hours for twice the money by going with the Super Hornets. You'd get better performance too so the Super Hornet would be the better option. However if the HUG's cost less than half or had less than 50% of their life left then the Classic hornets being upgraded would have been a decent option. As this wasn't the case the HUG program was a bad choice and in hind sight we should have purchased Super Hornets.
Ordering the super hornets in 1998 would have allowed the Classic hornets to be shared amongst a fewer squadrons. Resulting in them never having to be rebarrelled. They would have retained the APG-65 and could have performed the low end missions. Australia would then have recieved the APG-73 which they wanted but instead they would be in a new super hornet airframe.
Its not too late to avoid the centre barrel replacement program completely. If a third squadron of Super Hornets were purchased to be used by one of the classic hornet squadrons, then the Classic hornets could be shared and they would then last until the F-35 arrives.
I also dont see why purchasing a third squadron of Superhornets would affect the F-35 purchase. The money to purchase a new aircraft does not come from a singler years budget. It is included in many budgets across the years. By purchasing a third squadron of Super Hornets it would indeed use up some of the money budgeted towards the F-35. However you must remember that we would be able to delay our purchase of F-35's by as much as 5 years. The money saved in that extra 5 years would be more than enough to allow us to still pay for the original total of 100 F-35 aircraft.
If i was in charge right now. I'd cancel the CBR program, order an extra squadron (24) superhornets and allow the classic hornets to be flown less and last until the F-35 arrived without the CBR program.
It may be too late.. which is good because i'd be out of a job