Problem with Betsy, (beside the fact she's a "mean girl" which I know from someone who knew her personally), is she doesn't want standards, she supports for profit charter schools (we've seen how well for profit colleges worked!) and fought accountability - her real agenda is funding conservative Christian private schools and defunding "secular" education.
Elizabeth Warren would not do well with moderates, she plays to her crowd the same way Trump does, she's bright but limited, like most elite law school professors she has little understanding of economics despite writing on bankruptcy law (I had her co-author for my bankruptcy professor) - she's more effective as a gadfly than she'd be as a President.
The real problem for the Democrats is the domination of the party by California, NY and New England.
They've won with Carter (Georgia), Clinton (Arkansas), Obama (Illinois).
Gore lost because he ignored Tennessee in favor of the liberal circuit in Washington, D.C.
For the Democrats to win in 2020, they need to find a heartland candidate, and for the left wing to accept a seat at the table but not a deciding voice.
The only way to get this country to accept a progressive agenda is to "boil the frog," that is, gently raise the temperature.
The mistake the Democrats make with social issues is to try and force them down the throats of middle america.
The "victory" on gay marriage emboldened overreach, better had they obtain "civil unions" and upheld the principle that the government should determine civil rights and responsibilities with regard to unions (alimony, pensions, etc.), and not recognize marriage at all (i.e. leave that to religion and separate church and state), like in France.
The problem for the Democrats, like the Evangelicals, is not that they want tolerance and equal rights, but that they demand acceptance and social legitimacy for their views.
Government in this country can't and shouldn't dictate social mores, but only protect civil rights.
That is, you can't outlaw racism or homophobia (something called the 1st amendment) but you can outlaw actions to hurt people or deprive them of basic rights based on racist or religious beliefs.
If this country is to ever reach a concensus, it's going to require a return to civility and common sense, a gay parade that is acceptable in SF might be bad taste in Grand Rapids, but a KKK parade should be unacceptable anywhere. Kansas is not going to have the same mores as Miami, but Kansas shouldn't dictate mores to Miami, either.
The first step is to moderate language, the second to moderate demands we place on the "other" to conform to our desires.