Every presidential election is completely different. Following the discussion in blogosphere, it seems to me that many are evaluating 2008 in terms of what happened four years ago instead of recognizing this is a completely different election.
Not a single vote has been cast. People are looking at polls and losing their sense of perspective. In 1992 Bill Clinton lost a series of primaries until South Carolina, where he began to turn things around. Even if Hillary Clinton does win Iowa and NH, it does not follow she has the nomination. The nomination is not locked up until one of the candidates has enough committed convention delegates to win the nomination. To take any other view is to effectively disenfranchise thousands of voters in Democratic primaries.
The first contest is in Iowa on January 3. That is two months away. Two months is a long time in politics. Even if Clinton does not make any obvious mistakes, two months is a long time.
Here are few different scenarios of how this could play out, Edwards could win Iowa, Dodd could win NH, Obama could win SC, Richards could win Nevada and Clinton could still win the nomination because she has enough cash to take early losses.
Edwards could win Iowa and NH, and the dynamic of the debate could shift and he could go on to win the nomination.
Obama could win Iowa, Edwards could win SC, and the primary fight could go on for months.
Bush could start a war with Iran in March and the whole dynamic of the Presidential debate could shift. I hope and pray that there will be no war. However, if there is one, I do not believe people will rally to the President. I think they will recoil with horror, especially as the international fall out (crashing dollar, etc.) begins to manifest itself. A new war will transform the debate in ways I could not predict except to say I doubt very much that Hillary Clinton would be the benefactor.