Russia is said to be currently supplying arms to the taliban. Their goal there (to disrupt american efforts) would be the same as in NK. And China is NKs ally today, and has said they would assist if the US restarted the war (except if NK uses nuclear weapons). Both helped them during the Korean war. Both share a border with NK, making it easy for them to do so again. And both have been clear they don't want a pro-american state at their border (in Russia's case, on their western border).
If war breaks out, it's very likely it'll be NK+China+Russia again (unless there's a very clear wrong by NK). In other words, NK will likely have more military options than the article admits once a war breaks out.
But if NK uses nuclear weapons, that may change. Would China and Russia continue to back someone who used them? That's the question, and it's not a given that they would.