It may come as a shock to some people, but when it comes to the human race surviving for thousands of years to come, the odds are stacked against us. From weakening DNA to over population and all out Nuclear War. Things dont look so good.
1. Artificial Intelligence 20 Years

We are making computers and artificial intelligence stronger, faster and more powerful all the time, but when will it become to much? we could be facing an iRobot scenario sooner than you think. If they became so advanced that they developed the ability to think for themselves then perhaps they would try to eradicate the human race. Who knows.