TL;DR:
When people leave this planet, they will first be coerced by the promise of a more stable life - perhaps due to natural disasters on a global scale.
Soon, however, that choice will be replaced by force, ala mandatory evacuations.
Those that resist, and commit themselves to live and die on earth will reincarnate (eventually) into our final and most enlightened form.
Those that leave will devolve over their remaining lifetimes in the harshness of space.