Was Romney the leader of the GOP in 2013? Kerry the Democrats in 2005? McCain the GOP in 2009?
If your looking for a definitive leader, currently there isn't one, usually the party that lost in the last election goes without a leader till after the next midterm election when individuals arise
Clinton is selling books and keeping her name alive, she'll fade, although she will continue to define a lot of conservatives due to thier anything Clinton phobia