Maybe they don’t kill her. Only transfer her to another realm, where she is again a blue fairy and do her own things again. Let her go to the enchanted forest and let her do her magic to the people, who calling her. I mean she was only a plot device, but she was also refered as the origin power and I think you should not kill the blue fairy in a family TV Show. What next, killing the Santa Clause, the easter bunny or Bert from the sesame street.
But, ok if they do it. Hopefully she do something for Rumple. I mean if she would have believe him and help him to get to his son, without creating a curse. There wouldn’t be such a mess. Rumple was desperate. She should have known after a so long life that he didn’t give up to get to this world without magic and give him a hint that there were a magic tree he could use. He would be reunited with his son and the curse with the Dark One was over. WIN WIN. I didn’t get it, why she did not help. I mean why is she only helping the “Good” guys. It would be very sad if she sacrifice herself to someone that hate her, so that later he will help the fairies and his hate will fate (and didn’t race the rent again 😉 )
Heros don't get their Happy Ending!