I think that after they killed Neal, a character that was vital to the storyline, that the writers just no longer care about their story. They could kill Snow and Charming because the writers don’t care about writing a good story. Neal dying just randomly a few episodes into 3B to be forgotten as if he never was is proof of that. If this show made sense and cared about it’s character then Snow and Charming would be safe. The writers don’t care and anything could happen on this show because they don’t care.