The platform on which Bernie Sanders is running, although appealing to many, is setting up his supporters for a major let down. Most of what he is proposing will not be implemented by the a congress made up of two opposing parties. Only compromised solutions are possible and that will not satisfy the supporters he has geared up to think REVOLUTION.
This is the the same phenomenon that has transpired on the right with the Tea Party. The Republicans have long made promises about smaller government, reducing the deficit, repealing abortion rights, all ideals that appeal to their base but would never transpire under the two party congressional system. Hence, when the promises don't come to fruition, the supporters become more disillusioned about politicians and more set in their desire for extreme solutions. This further divides the electorate.
So, the Independent, self named Socialist Bernie Sanders running conveniently under the Democratic banner is ginning up the same sort of diversionary politics practiced by Tea Party Republicans whose policies will never become law. So by setting the expectation of his supporters that utopia is one vote away will surely lead to a more polarized population that exists today.