The only major character I think does not fall under the 100%-no-way-they-will-die category is Rumple and that depends on a few factors, the biggest being if there’s a S7 or not.
If there’s a S7, I think Rumple is more likely than others die (sacrificing his life for Belle/new kid)
If there’s NOT a S7, then I think Rumple is far more likely to live, having given up all the darkness once and for all.
I think a third option, depending on if there’s a Season 7 and Bobby wants to leave, is that Rumple and Belle decide to leave Storybrooke together and raise their new baby. I believe that’s been suggested before. As far as the writers are concerned, the bulk of Belle’s story revolves around Rumple, so what would be the point of keeping Belle on the show without Rumple? I also think that the writers do want to ultimately give Rumple some sort of happy ending. They just don’t want that to happen until either the end of the series or when Bobby wants to leave. They don’t find morally good Rumple interesting enough to write for in the long term. Hence why they just had to make him the Dark One again at the end of 5A. In short, the writers want to have their cake and eat it too.