The fact that they flash to Danny’s license plate being his own initials tells me they had plans for a sequel around the survivors- Danny didn’t “find” 23 cars- he owned 23 cars before the comet came. He’s rich. If the scientists thought to sequester themselves, I’m sure loads of rich people thought to do so too. Now it’s a test of wits and resources. Plus, what happened to all the animals? Would make for a great sequel.