I have mostly stayed out of the democratic primary this year. But if Sanders wins Iowa then he will have a viable (although still a steep uphill) path to the nomination. If he loses Iowa, then he is probably done.
New Hampshire won't matter because it is next door to Vermont and so no one will take a Sanders win there that seriously. And there is some logic to that. While NH is starkly different in its politics than VT, democrats in NH are a lot like democrats in VT. So winning over democrats in NH will not demonstrate that Sanders has the kind of broader support he will need to get the nomination.
New Hampshire won't matter because it is next door to Vermont and so no one will take a Sanders win there that seriously. And there is some logic to that. While NH is starkly different in its politics than VT, democrats in NH are a lot like democrats in VT. So winning over democrats in NH will not demonstrate that Sanders has the kind of broader support he will need to get the nomination.