If you look at most metrics normalized over the whole Earth, yes we are in an unprecedented era of peace, and we should be thankful. There are issues and there is room to grow. Daesh is an example of forces that threaten to unravel that peace, but are we going to kid ourselves into thinking that Daesh is anything like the beginning of the twentieth century? Let's not fall into recentism and forget what we learned in world history.
When it comes to values/nationalism and such, I think it sounds like your argument then is there is a potential for the reversal of such trends and I agree. But it's discussions like this that hopefully will keep us from repeating the mistakes we make in the 10's or 30's. We are live actors and we have a chance to change things for the better. You can tell that I'm pretty much an optimist.