Rebuilding and developing he NZDF combat capability is going to take years (as in 20 years), especially in the current fiscal climate. That said theres any number of things I'd like to see happen / proposed...
1. Reinstate the Macchi's and scrap the King Air replacement.
2. Third Frigate and OPV or another class of ship that's in between the two.
3. Improved Maritime survellience
4. Introduction of Harpoon / RBS 15 or the like onto the Orions. Ideally I like to see this capability with a limited land attack role.
5. Establishment of a standing Ready Reaction company or expanision of QAMR into a third battalion.
6. Upgrade of Frigates, including new ASW Torpedos. Wouldn't mind seeing the Orion ASW upgraded to.
On a point by point basis, here is my take
1. Reinstating the Macchi's IMO is of minimum value unless they are significantly upgraded with avionics, or are used to train fast jet pilots. That in turn would mean that some form of fast jet has been or will be added to the RNZAF inventory and an ACF reconsituted. As much as I would like to see that happen, I do not forsee that without either a significantly positive change in the economy, or a significantly negative change in the perceived sercurity environment. The King Air replacement I do not know enough about to have a real opinion at this point.
2. My concerns about adding a third frigate (or OPV) have already been voiced recently (in the RNZN I think?) There is a limit to just how many personnel the RNZN can add to the ranks in a given amount of time. Similarly, if the vessels are deployed frequently with only a small personnel pool to be crewed from, it will increase the likelihood that personnel retention will be an issue and sailors will not make the navy a career.
A potentially better approach would be to begin talks with the RAN about what features and capabilities the RAN is considering for their OCV. With RNZN involvement, the OCV minor warship programme can be a joint venture between Australia and NZ (not unlike the Anzac FFH) which could help some areas of the NZ economy. From a defence perspective, the OCV type vessel could be the sort of vessel the RNZN needs to carry out multiple roles (or be reconfigurable depending on needs). The OPVs which are now entering service should be fine for EEZ patrolling, SAR and other policing tasks. They might even be able to have some modules developed and fitted for disaster relief and some MCM work. However, they are whole unsuited to operating in anything other than a benign environment. Depending on what range of tasks is envisioned for the OCV, it might be possible to get a vessel which can operate in some threatened environments. By getting involved now, it would give the NZDF time to increase the number of personnel in the RNZN so that when the initial vessels launch, New Zealand can add them to the fleet without too much strain. As an added benefit, Australia is looking at getting something like 20+ OCV-type vessels to replace basically all RAN minor warships and survey vessels. This means that the programme cost per vessel is likely to be fairly low and could allow the RNZN to purchase as many as six over the course of the programme. This would allow replacement of HMNZ Ships Resolution and Manawanui, as well as the two OPVs, an additional OCV to provide year-round patrolling, and then a final OCV which could be used primarily as a training vessel. This would likely allow NZ to add a third frigate back into the fleet when the Anzac replacement programme comes along, yet not leave NZ vulnerable like it is currently if a frigate is away on a deployment and the other is in for a yard for maintenance or refit. A OCV would still be potentially available for deployment in case of a crisis.
3. Maritime surveillance should certainly be increased. I have mentioned some possibilities for a short/mid-range fixed wing MPA which I feel should be added to provide additional coverage. When the P-3K Orions start to be replaced, a minimum of 3 P-8 Poseidons or their equivalents (A320 MPA perhaps?) should be purchased. While it would be nice if NZ could do a 1:1 Orion to Poseidon replacement, I suspect that the significant costs of the P-8 will prevent that. What should likely be done then is for land-based navigation and surveillance radars to be positioned at various points around NZ territories to guide traffic and monitor the air and sea-based approaches to NZ. This could help both in detecting vessels or aircraft in areas that they are not supposed to be, as well as potentially providing more up to date last known positions in the event of emergencies. Additionally, the NZDF should start looking for a replacement naval helicopter. The SH-2G(NZ) Seasprite is approaching its service life mid-point, and parts have apparently been problematic. Between that, the fact that there is no commonality with allied naval helicopters after the RAN could not get theirs operational for a number of reasons, the Seasprites only being configured for ASuW and using a design from the late 1950's, it might be time to look for something else. It would be nice if the replacement was able to conduct both ASW and ASuW ops, which means the NFH-90 or MH-60R Seahawk would be candidates. However, something smaller might be desired, as I understand that an NH-90 is a tight squeeze in an Anzac FFH hangar. If the OCV's are equipped with helicopter hangars (and it would be foolish IMO not to equip them with hangars), then something smaller would likely be needed. I personally am rather partial to the navalized AS565 Panther variants. As a side note with that, if 6 OCVs are ultimately added, along with 3 Anzac replacements, then the 5 Seasprites would likely need to be augmented with 10 more naval helicopters, or 15 replacement naval helicopters ordered.
4. While it would be nice to introduce some form of mid/long-ranged AShM or land-attack missile onto the Orion, I am not sure that is a real possibility. IIRC the P-3K Orions were re-winged a few years ago as part of an upgrade/SLEP. However, the wiring connections within the wing were not upgraded to the current MIL-STD databus (1760 IIRC, but it might be 1553B) which means that the Orion could not carry the Harpoon Block II. Given the advanced nature of the RBS-15, I doubt it would be able to talk to that, and I am not too certain that it could be used with a Harpoon Block I, which is just an out of produciton AShM anyway. The only real way to fix that which I am aware of is to have the Orions get re-winged again, only this time have the wiring harness in the wing get brought up to current standards. Given the cost and time required, plus the limited service life remaining in the Orions, I am not sure it is worthwhile.
I will leave off discussing the last two points for now, as I have been rambling on long enough.
-Cheers