100% agree with all of the above.
The only justification I can see for some of the “make work” programs is for it to provide the kernel of a war economy. It’s worth paying for that option value, but the cost of that option needs to be minimised. We don’t do that by spreading our already sub scale operations across multiple sites (e.g. WA / SA for shipbuilding, QLD / VIC for armour).
Consolidate at one site, make it as efficient as possible.
Attempting to keep a capability going, in case there is a wartime command economy, is really not worth it for Australia IMO. If there is a production capability that, due to the size of orders to meet ADF requirements plus whatever exports might be had, that it becomes a break even or near-break even cost, that is a rather different story.
Unfortunately, much of the production capacity for vehicles and aircraft can be done rather quickly in dedicated facilities designed for large scale production. When one factors in the relatively low production number demands for ADF service, with planned long service lives, then if one wishes some of this kit to be built in Australia, they either have to face a very long time to produce the desired number of kit, at very low production rates (think like the time to produce classics like handmade Rolls Royce or Bentley automobiles) or much shorter, faster production runs which then leaves a facility and workforce idle once Australian demand plus exports have been produced.
An obvious problem with going towards a VLRP model is that it would take years before sufficient examples of the new/replacement kit have been built before there would be sufficient numbers to replaced whatever Australian kit was to be retired. This is also not taking into account whatever costs there would be for building or modifying the production facilities and establishing the skilled workforce.
If the decision were to be made to go with a normal mass production line model, then it would likely that most kit could be produced in just a few years to fulfill Australian orders. However, if the kit in question is expected to serve for 20 to 30 years, this could leave a production facility and just as important, the workforce, idle for 15+ years. Also there is a very real elephant in the living with examples like the M113 in Australian service. These entered service starting in 1964 and are expected to start (FINALLY!?) being replaced ~2025, after up to 61 years in service... IMO it makes little sense to spend potentially hundreds of millions of dollars building a site, then raising and training a workforce which will then all be made redundant after a decade or less, only for the process to be repeated again a decade or two later.
Naval shipbuilding is a bit of a different creature in part because what is being built is a custom product which by the nature of it's sheer size is going to take significant time to build just one of. Outside some of the yards in China, S. Korea or Japan, there is not really a good way to engage in 'mass production' of naval vessels. TBH the best example I can recall of mass ship production would be the US efforts during WWII to produce cargo ships known as Liberty ships, however these were vessels specifically designed to be simple and easy to produce, with a targeted service life of ~five years and these were cargo vessels, not combatants. The immense size and costs involved with such vessels also means that major maintenance and upgrades are significantly more complicated and require more infrastructure and more from a workforce than from much smaller kit like aircraft or ground vehicles. For instance, the 1.1 tonne GT in an M1 Abrams tank was designed to be removable and swapped out using a hoist in about 15 minutes. The LM2500 GT's using in RAN frigates and destroyers are rather more complicated to remove and replace if/when required. Having a facility and workforce able to do such work, or other things like removing an existing ship mast and associated wiring and sensors to fit a new mast and sensor fitout is also worthwhile and needful. By having naval yards which actually build these vessels, that keeps much of the money spent on a naval build programme in Australia as much of the material and fittings can be sourced domestically (how many hundreds or thousands of tonnes of steel and/or aluminium went into the frigates and destroyers?) as well as the wages for the workforce, with much of that money then going back into local, state and the national economy. This is where a ~30% cost increase for Australian builds still ends up being a net benefit to Australia. As a side note, that figure of ~30% is nearing 20 years old at this point, so it is quite possible that the percentage has changed though in which direction and by how much are unknown to me.
By maintaining a naval yard which can construct such vessels, that also maintains a facility able to maintain, repair or modify these vessels and just as important, keeps around a workforce which is able to carry out such work.
Australia IMO has sufficient critical mass to sustain naval ship construction, there is enough demand to ensure a steady flow of work to sustain facilities and personnel, provided politics and stupidity do not overly interfere. Unfortunately, much of the same cannot be said for much of the kit used by Army or the RAAF, although there could be opportunities for Australian industry to make components which contribute to a global supply chain.