There's a reason that Bernie Sanders is stubbornly refusing to concede defeat in Iowa, even though the difference in delegates between winning by a couple hundred votes and losing by a could hundred votes is basically nothing; and that is because Bernie Sanders' campaign is a dead man walking and he just doesn't know it yet.
Even if Bernie somehow manages to hold out until the Iowa Democratic Party somehow declares him a winner in a couple weeks, he has already lost. Hillary has claimed the victory and the media isn't much interested in correcting her, and so she's already gotten the PR boost from the win. Bernie never needed the delegates, he needed the bump from being able to stand up on election night and declare himself the winner in Iowa. He did not get that. He will likely go on to win New Hampshire by a relatively small margin, but then he is done for as the campaign moves to South Carolina and Nevada.
Nate Silver has already pointed out the problems that loomed large for Bernie Sanders even if he won both Iowa and New Hampshire. Bernie's base within the Democratic party is white, liberal voters. The state with the largest percentage of white liberal voters among Democratic primary voters is Vermont. But behind that are New Hampshire and Iowa at #2 and #3, respectively. If Bernie could not pull off a win in Iowa, where white liberal voters make up 50% of the Democrat voting base, he stands to suffer humongous losses when the campaign moves to South Carolina (where white liberals only make up 19% of the Democrat voting base) and Nevada (29%).
Bernie's one and only shot at actually beating Hillary has always been riding the momentum from clear wins in Iowa and New Hampshire to erode Hillarys' base of support. Having failed to do that, he has allowed Hillary to stay in a commanding position in the race and Bernie does not have another chance after New Hampshire to make a splash for a very long time.
Bernie will likely hang around, in the technical sense, for several weeks, at least through Super Tuesday. But from this point on, it's merely a statement campaign. The slim chances Bernie had of actually beating Hillary died last night, and his ability to continue to pull Hillary left with it.