The political pundits advising Hillary to move to the left in order to pre-empt a threat from Elizabeth Warren have it wrong. It is questionable if such a move will gain her any votes, but it is unnecessary to win the primary and will hurt her in the general election. In 2004 Howard Dean had the same crowd of radical leftist groups like moveon.org backing him. Up until the actual voting he polled great. Of course once the battle began he crashed and burned, losing to the more "centrist" candidate John Kerry.
In 2008 Obama started with the same supporters as Dean, but he won. There was one major and telling difference. Black voters represent about 25% of Democratic primary voters. and traditionally the vote is divided. Obama entered the primary and true to form it remained divided because no one thought he had a chance of winning. But once he won in Iowa, people realized he could win the nomination and the entire black community lined up behind him. Hillary would have won in a landslide absent the black vote, and would have won decisively had the black vote been divided. In 2016 the it will be divided, and Hillary will win the nomination easily. After all, wasn't Bill Clinton "the first black president"?