This is obviously not going to happen. Given the state of world finance and the willingness on the part of any nation or any group of private (read capitalist) entities to provide the financing needed to get a half dozen human organisms alive and in fully functional shape on Mars and given the huge costs of such en endeavor, this will not happen. The only other way - "we cease to exist" - seems the only possible outcome. Gaea will cease to support our species along with most other living organisms upon her surface.
To take a page from George Carlin's book, Gaea wanted "to simply incorporate plastic into a new paradigm: the earth plus plastic. The earth doesn’t share our prejudice toward plastic. Plastic came out of the earth. The earth probably sees plastic as just another one of its children. Could be the only reason the earth allowed us to be spawned from it in the first place. It wanted plastic for itself. Didn’t know how to make it. Needed us. Could be the answer to our age-old egocentric philosophical question, 'Why are we here?'