I love Bernie Sanders, not for his political views (I am to the left of Hillary but I'm probably to the right of Sanders), but because he is politically savvy, and that means everything for splinter candidates like him. I hope he does run and contribute to the narrative and, hey, maybe even win, and I thank him for not running independent should he fail to secure the Democratic nomination.
As for my vote, him vs. Hillary in a Dem primary, I'll vote for him.
I don't think he wants to be a fall candidate. That almost guarantees him oblivion in the Senate. I could see him doing well in small states like Vermont, Montana, etc.