Can we stop parroting the conventional wisdom that early polls are meaningless? Both on the left with Sanders doing better than expected, or on the right with Trump not going away*, you can't say that the polls don't mean anything. People love to tout Giuliani's poll numbers in August 2007, but that misses the point. It's not that polls this far out predict the winner. It's that they have a clear influence on: Debates, the ability of the eventual nominee to credibly do the etch-a-sketch thing, the eventual party platform, the view of the party to onlooking moderates (moderates, NOT independents who are generally undercover GOP types), etc.
Let me put it this way, if polls didn't matter, if Trump was polling 2% in Iowa, would Scott Walker have cowered and said, "his immigration plan is very similar to Trumps" and added that "we should have something like in Israel and Palestine?" (probably thought he sounded smart on this last bit when really he done effed up even more than Romney's "self-deportation" stuff).
Looking at team Blue, whether you support Sanders or Hillary, Sanders polling within touching distance in NH and having sizable national support is good because it will improve the content of the Democrat party platform for 2016, because Sanders is talking about good stuff. If people want to go out and see this Sanders guy who is challenging Clinton in the polls and pulling in crowds, that is GOOD.
* BTW, this is a separate issue but I HATE how the MSM frames Sanders = Trump. The MSM is really awful sometime.