The recent lack of main character deaths seems like a pretty silly criticism to me. The problem is the story - not the survivor count. I don't think it can be disputed that the show recently took a severely stupid turn with "the heist" north of the wall. It was a stupid idea and required all kinds of stupid contrivances to get the characters into, and out of, their predicament. Cut that story, and you don't have any of this discussion about how all the significant characters implausibly survived. (Jon somehow emerging from freezing water was easily the stupidest).
We'll likely see at least one major death in the final episode. I'm also guessing this is where the final of Dany's three betrayals comes to fruition, and it is Jamie once again breaking an oath to spring a trap on Dany for his love for Cersei.
My biggest curiousity at this point is whether the show introduces Howland Reed in the final season, or just abandons that story.