In a worst case scenario, the world population will continue to rise at a high rate, and soon overpopulation and food shortages pose a major threat. Luckily, judging from the rate of technological advancements since the 1700s, we're most likely going to see technology develop at a rate never seen before, so this could be used to mass produce food, or who knows...maybe establish space colonies? However, there is a downside to this. If technology and science do accelerate, then our messed up human nature could drive us to create far more destructive, secret weapons, and make the atomic bomb look like a shot gun in comparison. That could start another race for arms and a World War III, if we're not careful. I believe that our leaders will find a way to avoid this, though global warming is another issue, and if governments don't act fast, our climate is only going to get far worse. So, eventually these problems, particularly overpopulation, are going to force us to find a way to migrate away from this planet. Can't stay on good old Earth forever, so lets hope that NASA and other private space companies are up to the challenge, because otherwise, we're all doomed.