Poverty
<There has to be a way to provide people with the essentials of life (shelter, food, transportation & communications) freely. All people should be able to live without fear of ever being homeless or going without those essentials. That's the future to aim for. That's a problem to solve. The world cannot work on fear alone.
As long as these things have to be built or produced by human beings, they will never be "free," unless you enslave the producers. However, a free-market system in America and other nations has made such things far less expensive than they have ever been throughout history. The poorest person in America lives better than a vast majority of the rest of the planet. A cliche, maybe, but still true.