We're talking about changing everything—not just our abilities, relationships, politics, economy, religion, biology, language, mathematics, history and future, but all of these things at once. The only single event I can see shifting pretty much everything at once is our first encounter with intelligent, extra-terrestrial life.
The development of any of our current capabilities—genetics, computing, language, even compassion—all feel like incremental advances in existing abilities. As we've seen before, the culmination of one branch of inquiry always just opens the door to a new a new branch, and never yields the wholesale change of state we anticipated. Nothing we've done in the past couple of hundred thousand years has truly changed everything, so I don't see us doing anything in the future that would change everything, either.
No, I have the feeling that the only way to change everything is for something be done to us, instead. Just imagining the encounter of humanity with an "other" implies a shift beyond the solipsism that has characterized our civilization since our civilization was born. It augurs a reversal as big as the encounter of an individual with its offspring, or a creature with its creator. Even if it's the result of something we've done, it's now independent of us and our efforts.
To meet a neighbor, whether outer, inner, cyber- or hyper- spatial, finally turns us into an "us." To encounter an other, whether a god, a ghost, a biological sibling, an independently evolved life form, or an emergent intelligence of our own creation, changes what it means to be human.
Our computers may never inform us that they are self-aware, extra-terrestrials may never broadcast a signal to our SETI dishes, and interdimensional creatures may never appear to those who aren't taking psychedelics at the time—but if any of them did, it would change everything.