Speaking of unused planes Air NZ might have some surplus ATR's for the complimentary MPA role. Wouldn't be a bad idea, but they are a bit short of range for the Pacific (but the VIP's will have an improved level of comfort). Some standard C-130J with roll on / off capability would overcome that and provide more flexibility for the NZDF.
Using the ex-AirNZ F27's back in the 80s / 90s as an example this isn't a silly idea, however caution would be needed with respect to them having a fair bit if use under their belts already, and the need to keep mods to a manageable size & cost. As we're likely to see shortly, the KA350 have, it seems, been fairly easily set up with systems that will allow SAR and light-MPA taskings (weapons capability not required nor should it be tried with an ex AirNZ a/c due to cost of mods).
The only role I could envisage for them however is on 42sqn to complement their KA350 fleet. The latter are all fairly new aircraft so I wouldn't chuck them out, however as I do see 42sqn needing more legs with it's new AWO role (which is forecast to be 35% of their flying time) then why not add 3-4 ATR's or Q300's ex-AirNZ to the fleet at fairly modest cost and let them assist relatively unmodified with current 42sqn roles (AWOT, MEPT, light pax/freight transport) where appropriate and enable 42sqn to be able to stretch their footprint up into the Pacific Islands as part of the 'Pacific Refresh' (which so far seems light on actual action).
When I say light transport I'm thinking (in terms of pax) NZDF & civilian emergency services personnel...not so much VIPs, although to a degree the latter is a valid use of such a/c. The ATR or Q300 have the range to hop up into to the Pacific and once there could spend a week or so at a time doing their thing... whether it be helping the Island Govts or just an extension of 42sqn training roles (there's a lot of crossover in the 2 anyway).
I think the RNZAF lacks a 'holden ute' - a sort of Andover type niche. The KA350 sort of offer that role but they're a little too small & there aren't enough of them, the ATR or even Q300 could do that at modest cost. I know we'll hear the argument that the RNZAF doesn't need to get lumbered with another cast-off, but post-COVID means there will be zero chance of getting a brand-new shiny a/c to expand the current fleet and at the same time the market will be awash with fairly good quality 2nd hand a/c of a suitable type to act as that 'holden ute'.
It's probably unlikley to happen, but in relation to the possible use of ex-AirNZ aircraft it's probably the only practical use for them (IMHO).