1. Go with a very liberal candidate that is able to work well with a Dem Congress. Someone like Warren would be great.
Given that the Democratic Party is heavily reliant on Millennials, I would fully expect the party to try and recruit Warren to run in 2020 - If they are smart about this, anyhow. She is exactly the kind of candidate Millennials would turn out for, and her background / genuine character appeal make her a good candidate for the working class.
Or, I dunno.
The question though, would those voters see Warren as having sold out for Clinton, and see her in the same light?