Well, I think human nature has to essentially change for this to happen. Consider that there has never been a time in human history where war was not being raged. I hate to be a downer but I think humans are inherently destructive. Fascist ideology (Nazis in The Book Thief) did not develop over one night. It took generations of hate, persecution, inequality and violence in all its forms to produce such a toxic ideology. It would be easy to say, "Let's all share and accept each other." Unfortunately this will never happen. It hasn't for 10 000 years and won't in the relative future. But if you really need to answer this question, I would probably say that we need to evolve past money, tribal bias, power and greed. I know, easier said than done!