Which is more likely...

[old timey villain]

Hillary has rehabilitated her image mainly because she occupies probably the most non partisan position in the administration. Foreign policy hasn't been a major issue in this administration, at least compared to economic and social issues, so she has managed to stay above the political fray, jetting around the world.

This isn't to say that she hasn't done a good job as Secretary of state, and that she doesn't have a good shot in 2016. I'm just saying that for 20 years, Hillary has been a major target for the right for a good reason. Hillary the politician is seen as entitled, shrieking and inauthentic. At least this is how she has been portrayed for 20 years.

Anyone can enjoy a surge of popularity once they leave political office. I mean look at Jimmy Carter.