300-500 years is a long way from now and I think that most pictures are les than 200 years from now. I think humans will mostly live in giant cities with buildings that are selfsufficient in energy and water/air purification.
One thing I'm thinking though is maybe we'll find a way to change how we view transportation. I mean, we'll fake travelling physically and have some sort of mind travel using a device that makes you think you were there physically. I hope we don't get there but I think this is where we're heading.