I've said it before, and I'll say it again. Anyone that thinks they've seen the last of Hillary running for POTUS just don't know Hillary.
She's devious and has enough low cunning to find the right opportunity to (metaphorically) stab Obama in the back.
Yes, she is smart and ambitious but she's smart enough and ambitious enough to know that if she primaries Obama regardless of who wins the primary they both lose because the meta-narrative of democrat incompetence will have been set in stone. She would have to have such a groundswell of support as to steamroll all opposition, even the GOP before the general.
I don't see the moderate dems/indies making the Leia-esque plea that she is the nation's only hope and I don't see the Obama Brigade doing anything other than hurling barbs of racism at ANY would-be primary/GE challenger.
I'm sure Hillary only took this job to build her foreign policy credentials as she waits for 2016. I don't see much change in that except now she's been marginalized for going on 3 years. She made a big push with the Libyan war so she regained a smidgen of independence and public spotlight. Since she's bailing she wins BIG if Obama loses as she can say "See, I told you so!" and subsequently be applauded for having been a good soldier during her tenure while being prescient in her earlier warnings. If Obama wins again (my the long-eared Lord help us) what she does for the subsequent 4 years will be most telling.