Of course it is possible that the world could be suddenly hit by a giant asteroid, but such events are pretty unlikely to occur. We have no reason to believe the world will end based on information available to us. It is religious belief that gives people these ideas that do not have basis in provable, scientific facts.
The world will always live on. There is no evidence on earth that can prove the world will end. Is there theories? Yes. However, theories are what brings fear and tricks people into believing something else. The only thing that continues to end in our world, is people. Our generation is moving so fast that over time, it will fade out and die while a new generation is born. Society is always changing and ending but it still remains a part of history and will continue to live on.
I don't think the world will end in the next hundred years. Someone or something will still be here. However, society as we know it probably won't be here. Technology is advancing so fast, and with it, things change even faster. It seems like things have the potential to get much better, but we also have the potential to decline very rapidly.
While there are a lot of scary people out there with scarier ideas, this is unlikely. The concept of mutually assured destruction has kept us in check this long and should continue, even if the contempt rises. There is no incentive in blasting your enemy off the face of the earth if you know the same will happen to you hours later.