Bernie's narrative is that he's an outsider, but he has 20-something years in congress under his belt, and he's caucused with the democrats for most of that time. So, maybe it's not so bleak as you make it out to be. And I agree that getting a progressive congress in is actually more important.
Oh I agree he has a ton of experience. It's just that, while he caucused with the Dems, he isn't really seen as one and I think that's what will end up hurting him more than anything, especially since he's running for their nomination. Don't get me wrong, I'm still hopeful about him winning the nomination. But I dunno about the GE, and I definitely don't know that he'll be able to get much done if he gets into power. What I'm most worried about is that if it turns out he loses the nomination, the immense energy of his grassroots movement just dies out because people throw a giant fit. Even if Sanders doesn't make it, we need to continue to advocate for his vision if nothing else and support local candidates and the like that can help make that happen. The Dems and the left are waaaaaay too focused on the Presidency alone when the reality is we gotta focus on all the elections all the time if we want any chance to change things.
I hope you're right! I just remember that Obama built up a huge, unprecedented grassroots organization too and it disappeared after a year because people were disappointed in his lack of wand-waving to magically fix the country's problems...I just want young people like me to remain idealistic but also be somewhat pragmatic - advocate on the behalf of great candidates but also on behalf of noble goals and keep voting no matter how jaded we become.