@flob - I think you need to define your terms a little more. "Changing the path of our existence" - whats that mean? Species death? Becoming cyborgs?
Our increasing synergy with technology has been probably the most obvious, life changing, ongoing trend which is set to continue and possibly accelerate. Such changes can change culutres and societies. - The developing technology allowing us to shape, mould and utilize our external environment, and to shape, mould an utilize ourselves as well, with bio-implants would be my best guess.
The big downside, to me, is that a significant proportion of us could get wiped out pretty much at any time through a catastophic meteor strike ,and there is precious little we can could do about it either.This is a worrying prospect, but not worrying enough to put me off my thorough going enjoyment of day to day life :)