The Democratic party has moved considerably to the left, thanks in large measure to Sanders and in large measure to this moment in history.

Some of that movement is opportunistic, but a lot of it is heartfelt.

Purists may not like that, but thanks to Duverger's Law there is never going to be a 3rd party in national politics in the US unless we go to a Parlimentary / mutliparty system and that isn't going to happen, if it ever did, any way but through the two party system.

So there's no choice but to do an insider takeover of the Democratic Party and the DNC. It's happening. Get behind it and be strategic, and don't cut off your nose to spite your face.