Rise of radicalism (through anarchy and extremism) which will be the biggest challenge to the world security. Governments would need to increase their military expenditure thus cutting down funds for other important sectors like education and medical care.Dearth of natural resources - which our generation has exploited considerably, THANKS to our greed for indolence, money etc.Increase in world population would be putting more pressure on the limited land and resources our Earth can provide. The growth rates are quite high in African nations and some Asian (read South-West Asia) nations, though it is decreasing in some developed nations (which could be another problem for these countries).Lack of social life by engaging more time on superfluous things (and not going out and meeting people) would be the other. And research by various institutes have proved that social ties are associated with better health and longevity.