Who knows what could come out of the Singapore summit? Surely anything is possible when you put two vain, autocratic idiots in a room. (Sure, Trump hasn't blown up any generals - although I have often wondered whether the stories of movie style show killings by Kim Jong-Un have been propaganda pieces.)
I do wonder what might happen if, through some bit of espionage intrigue, Kim is struck down via poisoning or some other sophisticated assassination attempt while in Singapore. Would the faithful generals back home try to launch a nuclear attack, or would they think that it was a great opportunity to get rid of his dynasty? As to who would try to take out Kim: well, if the Putin plan is to bring disorder into the rest of the world so Russia can fill the vacuum, it seems to me that he may well think there could be advantage in it happening.
If I were looking after security in Singapore, I would be looking very carefully at any person with a Russian connection who happens to be in town.
Update: I didn't read this before I wrote this post, but I see that Hot Air has a post speculating on the security risk to Kim, too. It says a Russian cargo jet followed Kim's jet to Singapore too, with an armoured vehicle and a private supply of food. That would suggest it might be easier for Russians to cause him harm that I realised.