I don't know. I think you are putting way too much on the importance of the Scouring, IMHO. So far the first two films have shown pretty well what happens if you don't do something about evil, re: Theoden.
Also in TTT there was a sequence with Merry & Pippen at the Entmoot where Pippen said something along the lines of, "let's just go home Merry, we have the Shire." And Merry said that if they didn't do something then there wouldn't be a Shire left. I think that moment shows that the Hobbits knew what the stakes were.
Well, those are my thoughts anyway. Hope you had a good weekend.
You may be right, I just know how important it seemed to me when reading the book. And you are right the message is given a couple of times, I guess it is the culmination of the story as far as Merry, Pippin and especially Sam are concerned and it seems it will be difficult to tie up those ends without the scouring. But I'm going to enjoy it I'm sure!
So is the final scene the Grey Havens? What I'd find disappointing is if they neglect Sam's final cozy moment with Rosie..."Well, I'm back."