It is very possible we will wipe ourselves out. On the surface, this won't mean much to the earth, because species have been going extinct since there were species creeping around the primordial ooze. However, one of the two greatest dangers to the earth is a giant asteroid coming from deep space and hitting the earth.
Today, our modern greedy capitalist governments are trying to put weapons in space. These weapons might terrorize humans for generations, but they are also the fledgling technology required to destroy a 300 mile wide asteroid.
The second greatest threat to the planet earth would be a run-away greenhouse effect, and it is a very real threat. However, a human created global warming is not the only way that this could happen. Venus is an example of a naturally occurring run-away greenhouse effect. The human-driven global warming is hopefully an incentive to create planet cooling technology faster.
**Technology is the ultimate weapon we have to wield on behalf of the earth; the only thing that separates us from any of the uncountable number of extinct species in earth's history.**
I know the instinct is to say that we should be preventing global warming, but all of this anthropogenic damage that you talk about has come from the progression of civilization. We would not be able to create vaccines, clone organs, or do complex surgeries with incisions no wider than a dime if we still lived an (environmentally friendly) pastoral existence. We would not have the amazing computing powers that we do now, and computers will be integral to our ability to track asteroids or travel to different galaxies.
If we did all suddenly lead a sustainable agricultural lifestyle, we would not create the technology needed to prevent future ice ages (because human propelled global warming and earth warming-cooling cycles can actually both exist) at which point the agriculture based human race would be under threat, (and without asteroid busting technology we're all likely going to die anyways)
And it's not just asteroid busting we have to worry about, it's asteroid tracking, which I hate to tell you we are putting a poor effort into right now. It is possible that the first inkling we will have that an asteroid is about to hit us is the feeling of being on fire.
Obviously we don't want to just fuck the earth up, because our rate of technological success is not guaranteed to outstrip environmental catastrophe. We don't want poisoned air and water to kill off all our future generations of scientists.
Space is ultimately the only hope for the human race, and our greatest threat. We will have to master inter-stellar travel at some point, but until then we have to make sure a giant asteroid doesn't vaporize us all.