Hillary will be the Democratic nominee in 2016, if she wants it.
There is no second tier of rising Democrats. The newer House members were wiped out in 2010. The Senators are decrepit, except for a certain woman who will not sell nationally no matter how much the middle class gets hammered. There are few if any high profile Democratic Governors capable of going national.
Why do you think Bill Clinton did everything he did for Obama? Without Bill Clinton, Obama would be packing boxes today.
The Organizing For America structure built on the Organizing for Obama structure, widely credited with getting out the vote in key states allowing Obama to win those states by narrow margins, will be part of the deal.
A Clinton elected Obama in 2012, an Obama will try to elect a Clinton in 2016.