Given that we can not control population, and will not control pollution, habitable living space may become a luxury item rather than a commodity. I can see building environment controlled domiciles that house a quarter to half a million people with recycled water and air. Perhaps high protein crops grown on the roof to be more self sufficient. One would probably need real qualifications to get a space there. Only city people need apply; there would be very little personal space. Good old boys from the heartland would go nuts quickly (well, more so than they already are.) On the other paw, they could join the mad max crew on the outside of the dome.
Other popular options would be having a good fairy come and fix everything and turn all the coal into NY white cheddar. Unlikely, to be sure, but I won't turn down the chance for white cheddar...