I think writing Sanders off so far is certainly a bit too extreme. Sanders is actually faring better than Obama vs Hillary at this point in the election cycle. And they had more debates under their belt at this point and Obama started at a higher recognition point. I'm not saying Sanders is going to win, it's still nothing close to a sure thing, but the opportunity is still very much there.
http://www.realclearpolitics.com/epo...ation-191.html
Obama didn't even start polling near Hillary until right when the primaries began. He was at half her numbers for months and months before then.