I was just thinking about this - they can’t kill off all of the members, as that would be too drastic, and giving them all redemption arcs is completely out of the question because of time constraints. I also feel like it would be repetitive if the coven members were knocked off one by one like the Queens of Darkness because they need some time to be developed.
As well, the coven is supposed to be all-powerful, and there are not many characters who are able to face off against them (just Zelena, Regina, and Rumple). Judging from behind-the-scenes pictures, it appears that the curse is still intact well into the season.
So...how should the coven be defeated?