The more I read of George Martin's short stories the more depressed I get. I am now convinced that all of the main characters will die and the only ones left alive at the end are the secondary characters. This is a shocking revelation to most of you and many will doubt this. I will advice you to read his short stories and pay particular attention to the fates of the protagonists. I am also of the belief that some of the plot lines will end in a state of ambiguity. By that I mean some of the plot lines will not have a resolution when the story reaches its end.
George Martin is an elderly man and he may feel the need to have his main characters die with him. At least he doesn't want them to live on past his own time. This is sad to his readers and it does not make good reasoning to me but he is harsh and cynical. Many of his characters possess those same traits but we need to remember that there are many things about Mr. Martin that we do not know about. I think there is a little of him in the leading characters like Daenerys Targaryen and Havilland Tuf. George Martin would love to prescribe solutions to world problems if he could. Tyrion carries his cynicism and vulnerability in the pages. Jorah Mormont has his pragmatic and practical side that allows him to see through the fog of B.S. that otherwise blind the more idealistic characters. Some of his fans believe him a hippie but this is one hippie who isn't just about spreading love. He's not an advocate of peace at all costs. There is love in his stories but it's rarely the ideal love like we think of. It's rarely love between two unmarried people who deeply love one another, both virgins, get married, have sex, and raise a family. A George Martin romance will always have a fly in the soup.
George said in an interview that the end will not be an apocalypse but I am of the belief that it will not be an improvement over the current situation. I know many readers and fans are expecting peace, prosperity, economic boom, democracy, and the continuation of the reigns of the Targaryens, Starks, Lannisters, and Tyrells over their lands. I am sad to say this. I no longer believe that will be the ending. The land of Westeros will barely survive and expect the classic strongholds like the Red Keep, Casterly, Eyrie, Winterfell, and Highgarden to fall. It may be as some fans on this forum are predicting, the humans will lose the war and the survivors will have to migrate east by boat or land bridge.
The secondary and lower characters that I believe will survive are: Samwell, Jorah, Marwyn, Little Finger, Craster's boy, Ned Dayne, Varys, Alliser Thorne, Tristane, Rickon, Greyworm, Robert Arryn, Meera. A few other minor characters will survive. Many Freys will survive and a few of the Tyrells just because of their numbers.
The Hightowers have a knack for going with the flow. They don't swim against the power current. They have shown over many centuries that they know how to accept and adapt to change. I think they will survive. With the exception of the brief mental break downwhen Otto tried to steal the throne this family has shown wisdom and flexibility. The Freys who inherit Walder's knack for survival and willingness to swim with the current will serve them well. The Freys and the Hightowers are surviving but not because they're politically savvy. They know who they can dump on and who they can't. This is a skill that the Starks never figured out and never will. Someone like Alliser Thorne is a survivor and I think he will live through the end. Lastly, the screwups are not going to make it because our author is harsh to people who screw up (Catelyn, Robb, Jon, Oberyn, Robert). When you play the game of thrones, you win or you die. Cersei is mucking up royally and that's not increasing her chances of survival. One more thing and this is piling on the bad news, I know. Some will have fates worse than death. The others make zombies so it is only safe to assume that some of our main characters will get caught and transformed to wights.