@bjhulk,
I think earth is a small place in what is a multi-dimensional universe. I believe that if earth reaches a point where it can no longer sustain life, people will incarnate in a place unknown to us right now.
I would have to believe that is a worst case scenario.
The belief that earth will be transformed into a new earth exists in Christianity but perhaps it that idea has also found its way into spiritual beliefs outside of Christianity. New age beliefs about people becoming clairvoyant and spiritually aware in the coming decades are optimistic about people changing. I have to say, I'm not so sure about that.