Ha, yeah as others have said, what do you mean, you mean humanity, or world, or universe.
In my view humans will either wipe themselves or be wiped out by a pirate alien race or plague ,famine war, either way we will be dead before the solar system ends, which will be the end of the world, as for the universe, that a whole different matter,
Weather its through over expansion,,riping itself apart at the sub atomic level or through some bigger recycle function. So expansion, slow, stop and contraction, to go down to a point of almost infinet small ness and then rebounds back out(another big bang) or weather our univesre is in a space between to 'higher' plains, These higher universes, are like waves in space and time, membrains, these waves came together, and the bang started our universe,,there loads of info on the net so I wont bore you all.
These universes have more than our 4dimensions. Im saying four, there is more, we cant comprehend them,or even see them,,but the four ,hieght, lenght ,width, and time,
In this space between these two larger, mutil dimensional,universe, ours was created, and will be crushed as they come back together. As it did before, it created the universe. Hope thats not to bably.
This can be tied in with the ideas of hindu-ism, please dont take offense if Im wrong, but there ideas of recyceling life is the same sort of thing. its perpetual. never really ending ,but, it has a start middle and end. So makes sense in that way. If you want to get into the maths of it the problem really is getting two equations to ballance out,,,
Well, I dont know ,but human kind will be long dead or be in a 'higher' place by the time the world is going to be consumed by the sun. Cause that will be the end of the world, as the sun expands and englufs everthing up to the kyper belt. then cools condenses, expoldes and becomes a black hole sucking in the very fabric of space, and time itself. Some suggest these black holes with all there anti-gravity,gravity,matter sucking and such that these holes are infact the nothing that our universe was started in. If you allow me, the black hole get filled with matter, breaks it down,so that its squashed into an infinitly small space,,sound familar,, and from here all the stuff for a universe ready to build. so in side a black hole a new universe is started, on an infintly smaller scale ,,
Ha, thats gettin of the point, sorry for spelling mistake and babbling on. take it easy