On average, the safest bet you can make about the future in any particular direction is that it won't be much different than now. Most things change slowly. Some change comes fast, but is not important -- like fashion. A lot of important change comes slowly, so you can see where it is headed -- like demographics. There is a small set of fast moving important change that is hard to predict -- the known unknowns.
In the forecasting business, "known unknowns" are called uncertainties. Since you don't know which way things will go, you need to imagine more than one scenario flowing from that unknown. At the pivot of every scenario lies a driving uncertainty. If the uncertainty leans one way, the future plays out drastically different than if it leans the other ways.
In the 1950s the outcome of WII was a huge uncertainty. The entire world would unroll differently depending on who won. Usually past uncertainties seem obvious in retrospect. But at the time, they are a puzzle. Fifty years ago there were uncertainties about the civil rights movement in the US, about the future of LSD, about the impact of polio vaccines, about the level of literacy, about whether China could feed itself, and so on. In each case, more than one destiny for the question was plausible. Segregation of races could have been enforced, LSD could have been legalized, polio vaccine might not have worked, and so on. And the world would have been different.
Today we have new uncertainties. I made a quick list of current known unknowns in my own mind. These are questions with significant impact, yet with multiple, equally plausible outcomes. I have a lot of opinions and hunches about what might happen in the future, but the following are issues that I think are important, yet I don't have a guess about how they will resolve. I can see each going several different ways.
What, if anything, will slow down China?
Possible answers: internal revolution, population decline, environmental realities, absolutely nothing.
What information will people not share with each other?
They share medical records, purchases, dreams, sex fantasies. What about their taxes?
How many devices do we want to carry?
Ten, two, one, or none?
What will modernize Islam?
Will Islam's "Reformation" be political, theological, violent, or glacial?
How much bandwidth is enough?
We have enough pixels in a camera, enough hi-fi in our music, how many gigs/s before we no long think about it?
Will we trust governments or corporations more?
Who do we want to run our education, libraries, police, press, courts, liscences, and communication networks?
What is the "natural" price of a book, movie, or song?
Once distribution and production costs fall or disappear, what will we charge for creations?
Will (or where will) the future ever become cool again?
Optimism is a necessary ingredient for innovation. What will renew it?
How bad are the harmful effects of surfing the net?
Are the bad effects of short attention temporary, inconvinient, or fatal?
Is nuclear fusion (synthetic solar) economically possible?
Making energy like the sun does might too cheap to meter or as uneconomical as a perpetual motion machine.
When will Moore's Law stop?
At least 90% of our progress today hinges on cheaper, faster computation every year. Stop one, stop the other.
There are other common questions that I have strong hunches about (climate change, national ID, the Singularity, the Tea Party, peak oil, Dec 12, 2012) so I don't consider them uncertainties, although others might.
As I think of more, I'll add them.