Actually there is a lot to read about the possible reasons for the death of Kim Jong Nam. Beside all those theories I also like reading tea leaves:
A group inside the elite (possibly from the military or security circles and not from the Kim dynasty) works as a stand-alone organisation, willing to build up another type of regime. Their aim is to eliminate the Kim bloodline and all who are loyal to the Kims.
Since approximately three years there are concrete plans to conduct a covert, maybe a clandestine operation, targeting the elite in North Korea. Those people took a look into the Kim family and draw a huge graph, conducting Social Network Analysis. They studied M. S. Granovetter, “The Strength of Weak Ties” (1973), and came to the conclusion, that „removal of weak ties, starting from the weakest link and working up, caused the communication network to break apart, while the removal of strong ties had little effect on the overall integrity of the network.“
Remembering the words of a North Korean security adviser, working now for the South Korean government and assuming that Kim Jong Nam was a weak link: This was the first strike against a target, very easy to reach, conducted by outside forces who want to overcome the regime and therefore they have to overcome the Kim dynasty.
This leads to the question: Who will be the next target?