As you said, she won't run. If she did, she would likely have better odds of stopping Clinton than anyone else on the left. College kids and progressives love her, but she's too far left of the American mainstream, especially after 8 years of Obama. She would get decimated in a general election by any but the weakest Republicans (she may beat Bush, Santorum or Jindal, but even that would be a long shot. Cruz would beat her easily.)
And what evidence is there for that? National polling on Warren is useless due to low name recognition. It should also be remembered that the only reason that Brown made it close against her was his relatively high approval ratings in Massachusetts (there's even a consensus on this forum that Brown could have won the governor's race this year if he ran).
From what it seems, there is a huge, bipartisan opening for a populist campaign against the banks and for better student loan practices. Warren seems to have no problems raising large sums of cash. And most importantly, as long as the Obama coalition holds, it seems that the race is a contest for the Democrats to turn out as many voters as possible. Remember, Obama lost among independents against Romney pretty badly and lost white voters among the largest margins in history.
IMO, Warren is probably the strongest candidate the Democrats could run besides Clinton and Gillibrand.
