If the plan is to deviate from one fiat to jump onto another fiat then I don't really think it's a good plan. Have a look at the recent Dollar Spot Index in light of certain events:

 
It clearly states the weakening of US dollar in past few years. But currently if you see the last end of the chart there is a sharp downtrend on the very last point. Considering this it's obvious that US Dollar would be affected if there is an outbreak of war but the point is that even Euro isn't much different from Dollar. So what's point of using Euro in place of Dollar in such a condition? Moreover weakening indicates inflation for US and pretty much growth opportunities for other countries whose currencies will now have atleast some purchasing power in USA. Moreover if you are looking for safe asset nothing is a safe asset when it comes to deviation with news. Have a look at gold's recent chart:


if you ignore the 10 day MA and look at the spot index see how sharply gold has had it's ups and downs.

Moreover we all know how volatile bitcoin can be in events of war and bad news. So I think it would be stupidity if we look for some other currency merely because the previous one is weakening due to a war.