I know that predictions have a way of being wrong sometimes, but it doesn't seem likely that Hillary Clinton will be the next Secretary of State.
She's aiming for the Supreme Court, if nothing else, during Obama's presidency. If Obama gives her the Secretary of State position, then she is out of the national scene. No landmark court cases on the Court and no major bills if she's in the Senate.
Of course she'll be on a lot of high-profile trips, but she'd get more attention as one of her party's leaders in the Senate. And another angle: if there's a problem in foreign policy, she's the Secretary of State. It could be her fault for angering the Iranians or getting the North Koreans to start their nuclear weapons program again. Obama can play that against any of her future ambitions.
I can see why Obama may want her to be Secretary. But I don't see why she'd take it.