Political revolution has to be from the ground up, not top down. Bernie talks a good game about this but the simple fact is that even if he wins, he will only have a very small window before the GOP regain their footings. I can't help but feel that he's overestimated the strength of his campaign. It's one thing getting people riled up in a presidential circle, another thing entirely when politics no longer dominate the airwaves and TV. People will return to the mundane tasks of their daily routine, get disheartened when nothing changes and stay home the next time.
The presidency should be the ultimate goal for progressive grassroots movements. Win the states legislature, governorships, house, senate first, then get a Bernie Sanders into the WH.