It's never ruled out until January 2016.
Basically.
I predict the future:
'After many long months of consideration, after talking to my husband and daughter, I have decided to form an exploratory committee on becoming the next president of the united states...'
She'll have both Obama and Bill Clinton campaigning for her. She will have the experience of Secretary of State, US Senator and First Lady under her belt. I think losing 4 years ago has softened people on her. She will be battle tested and fierce. And she gets 2 years off to just build up her network and campaign. No way she isn't running.
I can't think of another candidate more qualified. I don't want to hear any bullshit about her age. She will have Obama and Bill Clinton unanimously behind her. That's like playing spades with the Big and Little Joker in your hand. She'll just copy some of Obama's ground game, internet style and bring a hell of a resume.
I wasn't a supporter 4 years ago but I would say she is as qualified as anybody, including the current president. Obama's style, Billy Boy's bipartisan swag and speech writing, she's much more personable and she's executing Plan B well. Disappearing into foreign countries to solve problems. She takes away so many cards from Republicans (excitement for the first woman president, great foreign policy record, centrist record). I can't wait.