For Kim Jong-Un, I doubt that much would change. The dynasty has been stable for three generations now.

https://en.wikipedia.org/wiki/Kim_Ju_Ae

She made her first public appearance alongside her father at a missile launch in 2022. State media initially referred to her as Kim Jong Un's "beloved" and "precious" daughter before adopting the adjective "respected", which is typically reserved for the most honoured members of North Korean society, such as Kim Jong Un himself. After her public debut, analysts of North Korea speculated about the reason for her prominence in state media, with some hypothesising that she was being trained as the heir apparent to lead North Korea. In 2026, the NIS reported to South Korea's National Assembly that she had finished her training and had become the designated successor of her father.

For Putin, my suspicion is that whoever replaced him would likely be authoritarian. That is, they've effectively got a functionally one-party system with a group of people at the top who are invested in that system continuing. It might be the case that some people feel differently about invading Ukraine, say.

Trump would be succeeded by Vance. I would guess that stuff like the "rename various bodies of water" or whatnot things would stop, but Vance is an isolationist, not an internationalist, and I understand has, if anything, been the source of stuff like not wanting to be involved with Ukraine. I don't know about some of the stuff that I'd call breaking conventions around use of executive power; my guess is that Vance would be better.

Throw in Xi and Bibi and you're looking at worldwide peace.

Now imagine we removed the systems that installed them and their successors!

If it happens closer enough, they'll be thinking twice, like they're a death note or something.