Just Australia, UK, Canada and the US? I am sure that both Japanese and South Korean superyards will feature in the Future Surface Combatant Capability race as they have also started active frigate programmes using MOTS systems from global suppliers such as RR, LM and BAE and are actively seeking exports and more than capable of delivering results.
When I look at the programmes either the ROK Navy or the JMSDF are currently running, it seems that the production runs are most likely going to be completed prior to the 2030 time frame, and/or the vessels are most likely too small or large for NZ needs.
Looking at the ROK Navy, it looks like there are currently plans to build additional units of the following classes
Sejong the Great-class destroyer (KDX-III), which is an Aegis-equipped 11,000 tone DDG and IMO far, far more than NZ would be looking to get. There also seem to be plans for the ROK Navy to order about six examples of what are being referred to currently as the KDX-IIA destroyer, which is to be an Aegis-equipped version of the Chungmugong Yi Sun-sin-class destroyer (KDX-II) though it looks like the planned production run for that would currently end around 2026. That would still be building an Aegis-kitted destroyer in the ~7,000 ton range which is potentially more than NZ is looking for. Lastly there are the examples of the FFX programme, with the
Daegu-class (FFX-II or Batch II) currently in production with 1 of 8 built, 3 currently in production and 4 more planned, or the ~6 planned for Batch III, with Batch III examples possibly in production when the RNZN
ANZAC-class frigates are to be replaced. The concern here is that the
Daegu-class is about the same size as the current RNZN FFH and might be too small to meet RNZN requirements in the 2030 time frame.
Looking at current Japanese build programmes, the ones which are currently active look to either be ending far earlier than NZ would be ordering any vessels, or much too large or small to meet NZ needs. The
Asahi-class destroyer (only two planned) had the 2nd example laid down in 2016, with an expected in service date of 2019. Also, a pair of larger/improved versions of the
Atago-class destroyer were ordered in 2015, which IMO would be much more than NZ would want, since the base
Atago-class DDG is itself essentially a scaled-up, 10,000 ton version of the
Kongo-class Aegis DDG. As useful as the Japanese Destroyer-Helicopters would be, I just do not see any getting up in the RNZN as they are too large (19,000+ tonnes). Also the Japanese-built warships tend to have a premium price and use weapons and systems sourced from Japan. This works for the Japanese as there is a national security interest in sustaining domestic design and build capabilities for both entire platforms and mission systems, there is a cost to do so which I doubt NZ would be interested in paying.
IMO if NZ were to order warships which were not part of an existing frigate or destroyer build programme involving a 5I's partner nation, then it would most likely be a licensed production build (perhaps with some minor modifications) carried out in an overseas yard that is able to do a low cost build due to the volume or work. There might still be a few European yards which could do this, or S. Korean yards like DSME.