South Korean vehicles would be cool to have in game, but the big dilemma is where they should go.
Personally, I don’t really want a Korean tech tree. Even if it’s unified, it’ll be Israel 2.0 in many ways.
As for Japan, I’m sorry, but the case for South Korean vehicles in their tree is really, really weak. Even if we were to factor politics out (which we shouldn’t), Japan has and had nothing to do with South Korean vehicles. They don’t use them (or vice versa), and they had no role in their development. The argument is basically “they’re close by!” which would be like someone saying, “Italy struggles with top tier, they need to get a Leclerc, they’re close by!” and you might laugh at that, I would too, but it’s the same logic. Yes, I’m aware that Japan is struggling with a lack of vehicles, but that shouldn’t give them the right to pilfer tanks from another country because of geographical proximity.
In any scenario, Gaijin has said in the past that they won’t add SK vehicles to Japan, because the only thing they have in common is both being countries in East Asia. And they could’ve added the K9 to the Japanese tree, but they added it to the Swedish one. They could’ve also added a ROKAF F-16 to Japan’s tree, but they didn’t. Seems pretty clear where they stand on this.
As for where they should go, perhaps just add them on a case-by-case basis, where it makes the most sense. There’s already the VIDAR in the Swedish tree. For example, the K1 should definitely go in the American tree, because it’s a derivative of the Abrams, and GDLS was heavily involved in its development. Whereas the K2, that’s a bit trickier. You could just add it to the US too, but people would say the US doesn’t need it. If a Polish tree is ever added, it could go there. It could also, hear me out, go in the Swedish tree, since the Norwegian army considered adopting it. Yeah, that’s quite flimsy, but I’m out of ideas here.