Bernie Sanders' message implies that Democrats can regain a lot of WWC voters. A lot of upscale white voters they have are Democrats because the party is a neoliberal and socially liberal version of a moderate Republican Party.
The day the WWC unites with downscale minority voters is the day the Democrats become the majority party. And probably within the next decade or 12 years we will see that happening.
A coalition between working class whites, Blacks, and urban voters would be unstoppable. And yet the party still thinks the future is in the suburbs?
I don't have another logical direction and believe me I originally believed that there would be a upper class college white - minority Democratic majority coalition. But it doesn't make sense because these groups' economic interests are mis-aligned. Upper class whites don't like tax hikes to pay for a lot of things as much as the working class whites. They are also vastly more conservative.
The coalition you point to would be similar to the great Democratic majority of 1932-1980. And working class whites have a lot to like in a populist Bernie-led Democratic Party that focuses on the worst effects of neoliberalism and tries to create an "equitable capitalism." Which is a very powerful message to all of the people listed in the aforementioned coalition. Their binding tie would be correction of neoliberalism's excesses and to make growth a thing for the lower and working classes.
For the record, the aforementioned coalition makes the Democratic Party an easy majority in the House and somewhat, the Senate.
Ultimately, I think upper class whites are destined to be a swing group, leaning Republican, while the working class goes home to the Democrats.
Let's take Pennsylvania under this coalition for example. I think Philadelphia and Pittsburgh go Democratic, but so does Erie County, Lackawanna, Allentown, and combined, they're enough to equal about 55% of Pennsylvania? (I'll do the math on that, shortly). Republicans would need some of the rural areas + the suburbs of Philadelphia to prevail in the state. But the GOP would be weakened if some of their small counties didn't return Republican thus increasing their reliance on the suburbs.
You get the idea, this is in a scenario where the GOP is the national minority coalition.