What A Wonderful World This Could Be

I just had a movie night with the family. We watched the movie Wall-E. This movie is set on a planet Earth that has been abandoned by humanity because pollution and waste have made life unsustainable.
The kids loved the movie. One disturbing aspect of the film however is that after being abandoned by humanity, it took 700 years for the first plants to reappear.
At bedtime, as I was tucking my 6 year old into bed, she asked me if I thought the Earth could ever end up like that.
I had to answer her honestly. I told her that if we didn't change our ways it sure could, and that there were places that were already like that. But then I also told her how there are a lot of people that are working very hard to make sure that it doesn't.
I told her how the world has already changed in my lifetime. That we didn't do any recycling when I was a kid, and had never even thought about it. I told her that it looks like cars probably won't be running on gasoline anymore when it comes time for her to start driving, and that will mean a lot less pollution. I also told her that we do what we can to make the world a better place, by voting for leaders that care more about the planet than making the companies in our country richer. I told her that as the problem gets worse, our leaders will work harder to solve it, and that I think the world will be okay.
But I honestly don't know if it will. And I fear for the future my children will inherit. It's a feeling of terrible powerlessness.