I think future worlds will change earth entirely; there will probably be teleports and other, various new machinery that could revolutionize the way humans live and survive. Working may be a thing of the past if Robots start taking shape.
Various kind of medical advancements might change how long we can live for; eternity might be possible in years down the track, that would make earth very crowded and we humans possibly would have to move planet and inhabit another land and environment, this could also make us evolve and we might need skills like wings or gills to help us survive the new living conditions.
Other forms of life might be on other planets and cross breeding between ‘alien’ and ‘human’ might have an effect on the physical and mental changes of humans. If life down the track ends up like how it is stereotyped, then hover cars and flying cars might be the way we transport. Food might also be different, due to the fact that we are killing off animals as a source of meat. Plant life might also die off due to those same reasons.
Another possible outcome in the future is the ice caps could melt, causing humans to become water bound, this could either wipe us out, or we could maybe adapt to these changes and change the way we can survive the new prominent element.
War could also be another way the world is changed, as much is it is a horrible thing, it could help out thinning the numbers of humans populating earth. War could also make people in general poorer, which might stop the rapid growth in technology. After a war, lots of jobs would become available to repair, make or farm new things to help things improve and to regenerate growth in the world. The downside to wars is, smaller countries could be over run, many people die, families lose loved ones and people are forced to live with such vivid memories while fighting.
The way the world is, really does depend on how us humans can maintain earth’s natural resources and how much the technological advancements can improves or hinder the way the world develops. Technological advancement to nuclear warfare could put an end to the world all together, Australia alone has 23% of the world nuclear power, if sold to the wrong people, the world could be gone or heavy mutation could occur, changing life form.
A future world, at the moment is really just your imagination, there is very little knowledge of what the world will do, is there really a god? Will there be an Ice age? No one can really know for sure just yet, it is all an assumption and what you think in your own head.