Art is powerful, but it's not that powerful. War is in our blood. You're asking wild-born wolves to behave like domesticated dogs just because they have enough food. Heck, even domestic dogs can be pretty vicious.
However, that doesn't negate your point that we could end up ruining it all through war. The thing is, most people want to follow, and they aren't very choosy about who leads them. Leadership tends to attract the kind of people who enjoy power, and so, even if resources are abundant, there is always something to fight about.
The technology that could bring about a lasting peace wouldn't be robotics, it would be some social mechanism through which we could obtain wise leadership. Which is certainly possible. Information technology opens up the possibility of entirely new levels transparency and accountability. Alternatively, there is the possibility of extremely rigid population monitoring and control.
Frankly, I think the most likely possibility is that there will only be a very brief period of time (maybe 50 years) between the point where we can automate all manual tasks, and the point where we have AI or augmented human minds, that are (by definition) impossible for us to predict.
A huge standing army will no longer be necessary. In fact, this is already slowly happening.
Firstly, human beings are omnivores, not pure predators.
Second, human beings have been evolving under the selection pressures of hunter-gathering lifestyles, semi-nomadic pastoral, settled farming lifestyles, and urban lifestyles for thousands of years now. The new lifestyles have been bred into our genes.
Third, if we really had no potential to behave like civilized people whatsoever, we wouldn't even feel morally drawn to civilized behavior at all. If we really were pure predators, "wild-born wolves", we simply wouldn't like cooperative behaviors or institutions whatsoever. The fact that we feel one mode of behavior is more moral is actually an indication that we are capable of that behavior, provided we actually choose to discipline ourselves.
Now if you'll excuse me, speaking of wild-born wolves, I have to go listen to that metal song again. Seid ihr das Essen? Nein, wir sind der Jäger!
As a whole, we hunt species to extinction just because some old geezers believe a horn is an erectile dysfunction cure.
Yeah, we can invade countries to search for a magic cauldron retconned to mean an easter souvenir, but we can't protect our home planet from an ecological devastation that will surely affect the future generations because we are now adapted to urban lifestyles and everything else is somebody else problem.
Somehow Agent Smith was right with the virus classification.
Looked at this way war has at least two 'opposites'. I put opposites in quotes because I think there are far fewer actual binary dichotomies than people make out.
While I'm on the topic. Same for love. They say the opposite of love is hate. But whereas love draws people together fear keeps keeps them apart so you could also say that fear is the opposite of love. Looked at in this way love has at least two 'opposites'.
I wonder how many other traditional binaries could be broken?
What is that expression? "All's fair in love and war"
You can apply anything with anything.
War is just another expression of art.