What does a new Democrat-dominated party system look like?

[Agonized-Statism]

With the present crisis and demographic shifts in mind, starting this decade, what would a realignment toward an all-encompassing, undefeatable Democratic coalition capable of pulling off successive landslides look like on the map? Who would be included in a modern voting bloc as large as the New Deal Coalition? How long could factionalism be kept from spoiling elections?

For contrarians, how would a Republican equivalent to this scenario work?

[Agonized-Statism]

So the coalition would be exactly what it looks like now

I'm talking about something sufficient to lock down the electoral college by New Deal Coalition margins. Something to end the polarization keeping the map stable and balanced, where the Democrats become a true majority party. As evidenced by Trump, a Republican can and will win in this environment given the right drop in turnout.

[Agonized-Statism]

So the coalition would be exactly what it looks like now

I'm talking about something sufficient to lock down the electoral college by New Deal Coalition margins. Something to end the polarization keeping the map stable and balanced, where the Democrats become a true majority party. As evidenced by Trump, a Republican can and will win in this environment given the right drop in turnout.

Democrats will never be able to win by New Deal-era margins as long as the two parties remain as ideologically sorted as they are today.  The Dem's massive wins in 1932-44 required the votes of conservative, Southern Democrats and agrarians. 

Right, and this is a thread about a hypothetical new party system in which that's possible.

[Agonized-Statism]

Demographics aren't destiny.

No one's saying that, I'm asking what a near future party system where Democrats make up a definite majority would look like.