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http://www.fivethirtyeight.com/2008/05/black-youth-and-latino-turnout-and.html
It does a good breakdown on what we're talking about vis-a-vis voting trends, and explains how (some) of his weaknesses could be offset with younger and Latino voters (many of whom are young.)
But let me be frank and honest: If you think things are going to stay the same, then yes Hillary is more electable. Not by a lot, not by as much as some would have us think, but yes slightly more electable just based on the 2004 map.
Also Obama maintains that serious OH/PA/FL problem. But other than that it's just not as hard for him as some would have you believe. And that's hardly enough to make him unelectable.