The community is a bit salty towards NG so I pity the devs. Apparently, every step they take to help that faction will fire back. Ok, it's partially their fault due to overtuned bronzes like Nauzicaa or Spotter. But, trying to make changes to any other archetype will result in quite a massive outbreak of whining:
– Boost mill? Oh god, the worst that there is…
– Boost clog? No, no, no – Kolgrim is dead and let it remain so.
– Hyperthin? Not oppressive, but largely uninteractive.
– Soldiers? Well, there were trials 😀
– Assimilate? Let's not get back to those times when Braathens & Terranova dominated the meta.
– Statuses? I recently came up with some cards for that archetype (that for me lacks 2-3 flavorful cards) and they were not received well 😉
Only the spies seem to be a low-hanging fruit because the archetype plays on people's sentiment, especially the veterans of the game. Other than that – Nilgaard is, and probably will be, wildly despised so any changes here are almost bound to fail.
BTW, I think that Nilgaard is, in some sense, the most balanced faction. Look at their cards – almost every single one is used in some particular play-style and there are almost none dead cards. If that is the case, it's probably because spies are out of meta.
Source: https://www.reddit.com/r/gwent/comments/yxmy9p/i_do_not_envy_the_devs/