Could stinkbug eggs hatch with no stinkbugs around?

Yes. Insects don't really incubate their eggs; the only parental care for eggs is cleaning and protecting them, and as long as no predators come to eat them, parasites to lay their eggs in them, or diseases kill the young inside, the eggs will still hatch!

Stinkbug parents do often look after the hatched young, so they might have better chances of getting through their nymphal stage with the parents around, though.