It will affect bitcoin's value because most of the people will hide their wealth to cryptocurrencies,because it cant be destroyed or stolen which is why you need to hide your private key until the market has ended,why cryptocurrencies ? because if there will be a war today internet would stop and it means cryptocurrencies will still exist.
This might be the logic,but the thing is what if the internet was shutdown forever or those facilities that runs the internet would be destroyed by the war? how would these cryptocurrencies be revived? theres always be something that oppose to our idea which are going to give us more time to think of it,possibility is high that bitcoin is going to be the safe haven,but we shouldnt forget the opposite of it.