"That's exactly why I think trying to predict what the world is going to be like in 40 years is just about impossible."

Douglas Englebart had a pretty good approximation of what much of our information technology would be like today over 40 years ago.

http://sloan.stanford.edu/mousesite/1968Demo.html

Of course, this was because he put together all of the necessary underlying technology. I remember reading an interview with him in the 90s, asking him if he was surprised how fast technology was moving. He replied, no, he was shocked how long it took for the things he had working in the lab decades ago to reach the main stream.

It will also stay very similar. The outline of life in the 1970s vs 2010 is still fairly similar. Drive around in cars, live in a house, take the subway, read the newspaper, watch tv, go to the movie theatre, buy food at a grocery store, call people on a landline, plug stuff into the wall, use your fridge and hair drier, drive around in your RV, fly an airplane at supersonic speeds, rent an apartment, have a family reunion, go to the doctor, get surgery, take drugs, read a book, go to the public library, go to school, flush a toliet, use an AC, open the windows. The dragon ball Z live action movie, although pretty horrible has a pretty accurate deception how high school will look like in 20 to 40 years. Pretty much the same with more flat screens and computers.

"fly an airplane at supersonic speeds"

We consumers actually don't do that anymore: http://en.wikipedia.org/wiki/Concorde