She wouldn’t have a prayer in 2016 or 2020 if she didn’t. Unless she plans to run a Tea Party or other type of ticket.
You are correct. Let's not forget that Reagan endorsed Nixon in 1968 and in 1972. If he had not done that he would not have been able to mount a serious campaign against Ford in 76 and would not have been able to win in 1980.
He became president due in part that he was in it for the long haul.