What will change everything? The question itself and many of the answers already given by others here on Edge.org point to a common theme: reflective, scientific investigation of everything is going to change everything. When we look closely at looking closely, when we increase our investment in techniques for increasing our investment in techniques... for increasing our investment in techniques, we create non-linearities, — like Doug Hofstadter's strange loops — that amplify uncertainties, allowing phenomena that have heretofore been orderly and relatively predictable to escape our control. We figure out how to game the system, and this initiates an arms race to control or prevent the gaming of the system, which leads to new levels of gamesmanship and so on.
The snowball has started to roll, and there is probably no stopping it. Will the result be a utopia or a dystopia? Which of the novelties are self-limiting, and which will extinguish institutions long thought to be permanent? There is precious little inertia, I think, in cultural phenomena once they are placed in these arms races of cultural evolution. Extinction can happen overnight, in some cases. The almost frictionless markets made possible by the internet are already swiftly revolutionizing commerce.
Will universities and newspapers become obsolete? Will hospitals and churches go the way of corner grocery stores and livery stables? Will reading music soon become as arcane a talent as reading hieroglyphics? Will reading and writing themselves soon be obsolete? What will we use our minds for? Some see a revolution in our concept of intelligence, either because of "neurocosmetics" (Marcel Kinsbourne) or quantum-computing (W. H. Hoffman), or "just in time storytelling" (Roger Schank). Nick Humphrey reminds us that when we get back to basics — procreating, eating, just staying alive — not that much has changed since Roman times, but I think that these are not really fixed points after all.
Our species' stroll through Design Space is picking up speed. Recreational sex, recreational eating, and recreational perception (hallucinogens, alcohol), have been popular since Roman times, but we are now on the verge of recreational self-transformations that will dwarf the modifications the Romans indulged in. When you no longer need to eat to stay alive, or procreate to have offspring, or locomote to have an adventure — packed life, when the residual instincts for these activities might be simply turned off by genetic tweaking, there may be no constants of human nature left at all. Except, maybe, our incessant curiosity.