Levi is like the Tyrion Lannister in SnK, a fan favorite and if he dies all of humanity will revolt against sensei. lmao
OMG !!! first I have to say love your comment(love Game of Thrones), and second I agree they would not kill Levi unless they want shock and upset people.
I read somewhere before that the author originally planned to kill all the characters. That would have been so awesome! But meh, he won't do that now. Levi is an extremely-loved character, I think it would be such a risk for the author to kill him. He could lose a huge faction of his readers.
There is acaully a high chance that Levi will die they first introduced him in a side character manner but later on in the manga you slowly got attached you his somewhat bad ass attitude and tragic back story they even gave him what was needed in order for him to turn into a titan which could be used as last resort. But with the role they gave him if they killed him off now that would bring more focus to the main character Eren not only that but it would place a truly tragic death in the manga that could lead to the Finnish of this one and have people waiting for a number Attack on titan 2, since a alot of stories that have horror dont go out without a tragic death like Tokyo ghoul for example.