The surface world is finished, but the world is not at an end. Life continues and thrives underground: office tycoons commute and surf the interwebs. Blue-collar workers maintain factory equipment and support the drone workforce. Chefs and line cooks alike prepare ingredients fresh from the subterranean gardens to sustain the masses. Wizards plot and sling spells.
We thought the changing environment would spell the end of the human race. As usual, we underestimated our ability to adapt and band together when things got tough.
Life isn't perfect; we still have strife and conflict. Crime still plagues our boroughs and back alleys. Politics and religion still inflame the web with rants and flame wars. Access to wifi is still spotty in the tunnels.
But life goes on, even after the end of the world.