Don Young has been in Congress 42 years. He is now 81 years old. Might Sarah be thinking about succeeding him as Alaska’s at-large representative; you hate to speculate like this, but there is a possibility that he dies in the middle of a term (figuring that this guy is going to try to stay in the House as long as he can), and she gets elected in the ensuing special election.
Why would Mrs. Palin go from a Vice-Presidential candidate to being one of 435 House members? The House is a very poor platform from which to wage a future Presidential run.