If it happens then do you think that bitcoin will live anymore?
There's a big possibility of market crash, if there's a world war 3 but world war 3 is something that every country wants to avoid, because it will end every country's economic achievement, WW3 is very costly what the world achieved in the last 75 years ago will go to nothing.
We have the United Nations that will tried to solve all the issues that will escalate WW3.