One thing to remember about Bernie Sanders is that he kept getting reelected as mayor of Burlington because people basically liked the results of his ideas when they got to see them in action. As a congressman and a senator, he hasn’t been able to impose his will or vision on the political process but the country has learned to accept many of the ideas he first introduced as the mayor of Burlington, and he’s won over doubters in the local business community and in the Democratic Party leadership who initially thought that his ideas were loony and dangerous.
That doesn’t mean that he’d be successful as a president. After all, much like Obama or even Clinton, he’d discover that you can’t do much if Congress is filled with skeptics and obstructionists. But he’s worth listening to. In the long run, he probably will see a lot of his ideas win out, one way or the other.