Seems to me the thing about this is, even if things "go bad" it's very hard for them to be worse than the results of the two girls just going with the flow and being part of the town's whole deal would have been.
I mean, double suicide isn't really foreshadowed. It's more that they outright accept it as a probable and reasonable price to pay for opting out of the horrible empty pit of an expected life that they're being offered. So bad results are possible--but likely not results bad enough to make their actions regrettable or their decisions wrong.
On the other hand, most of the world wasn't as bad as horrible coal mining towns. Things might go surprisingly well. They've bet everything they have, which is nothing, on the possibility of something better even though they can't imagine it. Perhaps their courage will be rewarded. At the very least, surely they will see some part of the world not deadened by coal dust.
