I don't know about Kamala, but Warren probably would have won in 2016, and 100% could win in 2020. She would appeal to them like '08 Obama did. If you bring out some focus-grouped robo-candidate like Hillary who can't convincingly prosecute the case against the institutional agents rigging the economy and causing the decline in these peoples' standard of living, which is the focal point of their angst, you're probably going to get beaten by Trump again. Hillary didn't even pretend to speak to these people who have been left behind. She was constitutionally incapable of making that case because she was the poster child for the political class responsible. What these people want to hear is that that someone sees their perceived struggle and will fight for them. That's why they voted for Trump. Warren, like campaign Obama, has made that fight a central part of her political identity.
People are too caught up in justifying their shytty punditry/analysis in 2016 by assuming the worst of Trump voters. Many of these people voted for Obama twice, not because they forgot he was black, but because he went into their communities and spoke their languages, and connected with them. Rural doesn't automatically equal stupid or racist or sexist. They just have different priorities and worldviews. And legitimately so, because the modern age has been increasingly inhospitable to them. They have no role in the future espoused by centrist corpocratic, technocratic neoliberalism. Bernie and Liz are cut from an older cloth, and share with Trump many of the same targets (Big Pharma screwing you over by price gouging, Wall Street screwing you over by raiding the economy and not sharing the wealth, Washington is screwing you over by being in bed with these interests, etc). The difference is that Bernie and Liz are espousing an all-encompassing message that that speaks to these people without feeding their ugliest urges like Trump did.
Ultimately, I think what these people are craving is authenticity, which Trump, Liz and Bernie all have in spades. Trump is losing his authenticity with each passing day in office, so it would be a tragic misstep to put forth someone who cannot make that winning case authentically like Liz or Bernie (although he would be too old imo). Liz is the way to go in 2020.