The lack of help from the DSCC seems to confirm their shift from WWC to upscale suburban districts.
Are Democrats now the party of the Bloombergeois?
Unfortunately, it would appear to be this way. Sanders represents the end of an era, rather than the beginning of a new one. He represents the dying gasps of the non-college educated White element of the Democratic Party - the one that can actually transcend partisanship (hence his stunning favorability among Independents). He's the last holdout of the New Deal Coalition and its nearly finalized influence on the party. There's no one who can carry his torch for a reason; the rest are too steeped in modern Democratic politics.
Just look at the demographics of Trump's approval/disapproval numbers; Whites without a college education (not to be confused with White working class) are the sole group that yet approve of him, whereas the traditional backbone of the Republican Party, which had been Whites with a college education, have essentially abandoned him. This group still gave him more votes than Clinton last year, but now his numbers among them are abysmal. Democratic leadership knows who to pursue and will adapt their policies and rhetoric to capture that new pool of voters starting in 2018. It's why they're focusing on the suburban district in Georgia while ignoring Montana.
