From where would an hypothetical operation to kidnap Kim be launched? Likely from SK or Japan, right? So yes, China could retaliate.

The operation against Maduro was launched from countries in the region aligned with the US.

Us has these nifty things called aircraft carriers, which were used to capture Maduro as well. They can be in international waters, the choppers fly quite far. China would not retaliate against the US.

That is a bold assertion to make considering China literally did retaliate against the US in North Korea once already, to the tune of war. Kidnapping heads of states is an act of war. Venezuela can't defend itself, but China certainly will do whatever is necessary to secure its vassal if the alternative is NK collapsing and having US military bases on its border.

You also rule out the possibility of an invasion of Seoul, as though it would be "unfair" -- when you're advocating for and actively in the process of tearing whatever remains of the concept of international law to shreds, what makes you think PRC would be inclined to play nice?

Other than by launching nukes (and getting 10x on themselves) China has no capability to attack the US. I don't think attacking SK is unlikely because it's "unfair", but rather because there's no incentive to do so. The concept of "if you attack Cuba we'll attack Europe" is an old playbook for the commies, and I think was always a bluff.

My point is that since in this scenario SK would likely be involved in some capacity (granting safe passage, harboring US planes, etc) they would suffer retaliation by NK and possibly China.

I don't see what's unlikely about this, it's basically NK's defense strategy.

China knows about carriers, and tracks them carefully. They have built a variety of weapons to sink them, too, but I don’t think they’d need to use them: note how the raid on Maduro went so quietly that people have been looking for evidence that some of the Venezuelan military were in on it? North Korea has built up a lot more paranoia and China wouldn’t need to sink a carrier, simply ensuring that the NK military knows what’s coming as soon as planes take off and communicates that in a way which makes it impossible for any potentially disloyal faction to act short of declaring a coup (you can’t “accidentally” miss something the entire chain of command knows about). I detest the NK government but I’d expect that to be a much bloodier fight, especially after a huge warning.

> Us has these nifty things called aircraft carriers, which were used to capture Maduro as well.

It wasn't just carriers in Maduro's case. The operation was carried from multiple places, including out of Caribbean countries aligned with the US. The US was literally signing deals with those countries months in advance.

Who would those countries be in an hypothetical NK strike? Because those countries would suffer retaliation.