I believe that the most important issue that we face in the future is that technology is eliminating the need for human labor at an accelerating rate, while population grows and the need for people to make a living continues. Much like we produce orders of magnitude more agricultural products today with a tiny population devoted to farming, the same story has played out with manufacturing, and now with other industries as well. We face a future where we only need 2% of the population engaged in production. How will the other 98% make a living?
There are two possible outcomes that I foresee: a Marxist revolution where "the means of production" are socialized, or a drastic Malthusian reduction in human population to a level required by the economy of the future. Hopefully the proletarian revolutions of the future have better outcomes than the ones of the 20th century.
The consumerist capitalism of the 20th century is in a negative feedback loop that is destroying itself: competition is driving cost efficiencies that reduce labor inputs that reduce disposable income and reduce demand. This has been occurring for many years, and has been masked by an expansion of consumer credit since the 1970s that exploded in 2007.
I found a blog today that features this theme: http://econfuture.wordpress.com/, and I will be writing about it more in the future here.