Board Thread:General Discussion/@comment-4637931-20160516030610/@comment-25926288-20160516031228

I would say that the answer will be accepting their dark sides, not destroying them. That'll likely be the moral of the story.

Every season could be the last one, but I would say there's nothing to go on. Rumple is very, very likely to be the series villain and final villain, but we don't know what 6b would be about. That'll depend on 6a and if Rumple then reprises his role as villain or some sort of redemption going onto 6b.