First, what do we mean by the end of the world? Is it the Earth being completely disintegrated? Or just the end of life on Earth as we know it? Or the second coming of Christ? All three of these events would really change things, that is for sure and that is an understatement.
There are a lot of things that would affect life on Earth. Even if something catastrophic doesn't happen, like getting hit with a huge steroid (remember Apophis? Well it will be back in 2029 and 2036. Last time it past between the Earth and the Moon.), or the sun growing in size (it is and eventually it will swallow the earth or kick it out of the solar system), or the expansion of the Universe finally tears everything apart, or maybe it will reach a point where it will contract into a big "crunch". There sure are lots of "ifs", aren't there.
Actually, I think something a lot smaller will cause the end of the human race if we don't kill ourselves off first. Humans are the minority on this planet filled with life. Not all of that life is beneficial to humans. In fact, there are a lot of small organisms that feed on and live off the human body. A lot of them will try to kill you and some do. I believe that a virus or a bacteria will be the killer of all humans. As for all other life on earth, a nearby star will explode and rip the atmosphere from Earth and then all life (as we know it) will die off. Or the expanding sun will turn it into a charred cinder.
I think I will stop here before I completely ruin your day, so you all try to enjoy life here on Earth while she is still being kind to us, you hear?