I think during the world the prices will crash badly for the bitcoin and other crypto currencies as well. The reason is simple, during the war priorities for the needs changes quickly. If its world war then I am sure the first thing that will go down would be the internet . Everyone knows that without internet you can not run the miners neither the blockchain nor the core of it. So everything will crash there and off course people know very well that during the war every other financial institute will close down. The life would be more important and all the things needed for living will become priority. So money will be transferred to the fiat immediately after the declaration and thus everything will become zero.