Well, this is theory is going around other threads, so I’ll repost it here.
What if the candle comes back into the picture? Cora stabs Rumple with the dagger, which is supposed to kill him, but Snow uses the candle to kill Cora and save Rumple but now Rumple is magicless.
I think there are two reasons why that won’t happen
A Snow could care less if Rumpel died. Unless Henry begs her to save grandad, I don’t think she’d risk using black magic.
B Cora does not want his powers to possess her. The Dark One’s magic is a burden. She just wants him as her puppet (right with ya there Cora… though I would probably do different things with him)