Prostitutes and porn stars get off Earth
Seeing the state of the world, an escort or porn star playfully broadcasts a message to the stars saying they'll trade sex for a lift off of the planet.
1 week later, fleets of ships arrive around Earth willing to take them. Of course, once others start finding out about the aliens being genuine with their offer, more and more people start volunteering to trade sex for passage off Earth.
What happens to those who leave...and what happens when those who stay find out the Earth is indeed fucked and they don't have a lot of time left?
Young escort didn't have any family that doesn't hate her and went to the stars as she didn't feel she had anywhere to belong. She finds the aliens she winds up with are actually very caring and makes a good fulfilling life among them.
2. Evangelical pastor tries to use the exodus to argue that Earth is now free of sinners. Then they out human civilization is going to end in just a few years. Desperate to save their skins, they offer their family and then themselves up but the aliens aren't interested...though they do broadcast their "audition" and upload it to the internet for shits and grins.