Two of them already died and Mom and Dad as well. Jon already died and was literally brought back to life. There is no reason for Sansa or Arya to die. Bran is the new three eyed raven, if he dies then his whole story is pointless. The whole Stark family has been a tragedy and the remaining ones alive are seeking justice.
Then whats the point of this show? Have Cersi sit on the throne and the same shit that happens for hundreds of years continue?
I understand we are reaching the end of this show and people are hoping for more surprises this show is known for doing, but if the past few seasons have proved anything, its that things are ending up they way it supposed to be. Just look at this past episode: Dany saves Jon and friends. Benjin saves Jon. Jon doesnt die again, even though he probably could of been killed off multiple times by now. It doesnt have to be the Jon Dany, and friends live happliy ever after, but it also shouldnt have to not be that either.
We'll have to agree to disagree, because even though the Stark family has been through a lot of tragedy, that still shouldn't mean they should all live. And they aren't all seeking justice. Jon wants to save the world, Sansa wants power, Arya wants revenge. A character like Arya absolutely should die, since her whole character Arc revolves around death.
The main issue I have with your logic too is that it can apply to all sorts of things. "Why have X die if they already did all this?" can be said of every good person who's died so far on this show.
We'll see how things shake out, but if you believe none of the heroes will be dying towards the end in S8, I think you will be disappointed.
Also, for the record, I do think Cersei winning in the end would make for a better ending. She contrasts so well with the heroes of the story because she's the only one focused on playing the game. If she sees the wight walkers, she won't see them as some special existential threat. They'll just be more enemies that are between her and the throne. A character like that winning out would be like siding with cold reality against the high fantasy of the series end game.
"When you play the game of thrones you win or you die, there is no middle ground", Cersei is the only one who understands this and she should win because of that. It'd be a nice chilling ending for a show that's always been about backstabbing and power grabbing. In the end, the most conniving and privileged schemer won, what did you expect?